Kvpy 2012 Sb Sx Solution1
-
Upload
kunal-chaudhary -
Category
Documents
-
view
221 -
download
0
Transcript of Kvpy 2012 Sb Sx Solution1
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
1/43
GENERAL INSTRUCTIONS
The Test Booklet consists of 120 questions.
There are Two parts in the question paper. The distribution of marks subjectwise in each
part is as under for each correct response.
MARKING SCHEME :
PART-I :
MATHEMATICS
Question No. 1 to 20 consist of ONE (1) mark for each correct response.
PHYSICS
Question No. 21 to 40 consist of ONE (1) mark for each correct response.
CHEMISTRY
Question No. 41 to 60 consist of ONE (1) mark for each correct response.
BIOLOGY
Question No. 61 to 80 consist of ONE (1) mark for each correct response.
PART-II :
MATHEMATICS
Question No. 81 to 90consist of TWO (2) marks for each correct response.
PHYSICS
Question No. 91 to 100consist of TWO (2) marks for each correct response.
CHEMISTRY
Question No. 101 to 110consist of TWO (2) marks for each correct response.
BIOLOGY
Question No. 111 to 120consist of TWO (2) marks for each correct response.
Date : 04-11-2012 Duration : 3 Hours Max. Marks : 160
KISHORE VAIGYANIK PROTSAHAN YOJANA - 2012
STREAM - SB/SX
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
2/43
PAGE - 2
KVPY QUESTION PAPER - STREAM (SB / SX)
PART-IOne Mark Questions
MATHEMATICS
1. Three children, each accompanied by a guardian, seek admission in a school. The principal wants to
interview all the 6 persons one after the other subject to the condition that no child is interviewed before itsguardian. In how many ways can this be done?
rhu cPps] ftuesa izR;sd vius vfHkHkkod ds lkFk gS] ,d fo|ky; esa izos'k ikuk pkgrs gSA fo|ky; dsiz kpk;Z,d ds ckn ,dlHkh 6 O;fDr;ksals bl izdkj lk{kkRdkj djuk pkgrs gS fd fdlh Hkh cPPksdk lk{kkRdkj mlds vfHkHkkod ds igys u gks A ;gfdrus rjhds ls fd;k tk ldrk gS ?(A) 60 (B) 90 (C) 120 (D) 180
Sol. Number ways are rjhdksas dh la[;k =!2!2!2
!6=
8
720= 90 ways
2. In the real number system, the equation 1x43x! + 1x68x ""! = 1 has
(A) no solution (B) exactly two distinct solutions(C) exactly four distinct solutions (D) infinitely many solutions
okLrfod la[;k (fudk;) esa lehdj.k 1x43x! + 1x68x ""! = 1 dsfy,
(A) dksbZ gy ugha gSA (B) rF;r% nks fofHkUu gy gSA(C) rF;r% pkj fofHkUu gy gSA (D) vuUr gy laHko gSA
Sol. x 3 4 x 1! " " = x + 8 6 1x" + 1 2 1x68x ""!
1x2 " 6 = 2 1x68x "!
1x" 3 = 1x68x ""!
Ans. (D)Infinite many solutions.
3. The maximum value M of 3x+ 5x9x+ 15x25x, as x varies over reals, satisfies
O;atd 3x+ 5x9x+ 15x25x, tgk x ,d okLrfod la[;k gS] dk vf/kdre eku (M) fufEufyf[kr dks larq"V djrk gS&(A) 3 < M < 5 (B) 0 < M < 2 (C) 9 < M < 25 (D) 5 < M < 9
Sol. Let ekuk a = 3xand rFkk b = 5x
Therefore blfy, ,3x+ 5x9x+ 15x25x = a + b a2+ ab b2
=2
1[2 (a 1)2(b 1)2(a b)2]
# 2
1
(2)
Thus vr%, M = 1 (happens when tcx = 0)Answer (B)
4. Suppose two perpendicular tangents can be drawn from the origin to the circle x2+ y26x 2py + 17 = 0,for some real p. Then |p| is equal to
;fn fdlh okLrfod p ds fy, x2+ y26x 2py + 17 = 0 ij ewyfcUnq ls nks ijLij yEcor~ Li'kZthok [khaph tk ldrhgS] rc |p| gksxk&(A) 0 (B) 3 (C) 5 (D) 17
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
3/43
PAGE - 3
KVPY QUESTION PAPER - STREAM (SB / SX)
Sol.
Equation of chord of contact T = 0 w.r.t. origin is
3(x + 0) p (y + 0) + 17 = 03x + py 17 = 0By Homoginization
x2+ y2(6x + 2py) $%
&'(
) !17
pyx3+ 17
2
17
pyx3$%
&'(
) != 0
* For perpendicular coeff of x2+ coeff of y2= 0
1 17
3.6+
.9
17+ 1
17
p2 2+
17
p2= 0
34 18 + 9 p2= 0, p2= 25
, |p| = 5
5. Let a, b, c, d be numbers in the set {1, 2, 3, 4, 5, 6} such that the curves y = 2x 3+ ax + b and y = 2x3+ cx+ d have no point in common. The maximum possible value of (a c)2+ b d is
;fn fdlh leqPp; {1, 2, 3, 4, 5, 6} ds in a, b, c, d bl izdkj gS fd y = 2x3+ ax + b rFkk y = 2x3+ cx + d ijdksbZ fcUnq mHk;fu"B ugha gS] rc (a c)2+ b d dk vf/kdre laHkkfor eku gksxk&(A) 0 (B) 5 (C) 30 (D) 36
Sol. 2x3+ ax+ b -2x3+ cx + d(a c)x -d bIf a c = 0 & d b -0* Max. (a c)2+ (b d)= 0 + 5 Ans.
6. Consider the conic ex2+ .y22e2x 2.2y + e3+ .3= .e. Suppose P is any point on the conic and S1, S
2
are the foci of the conic, then the maximum value of (PS1+ PS
2) is
'kkado (conic) ex2+ .y22e2x 2.2y + e3+ .3= .e ij ;fn P dksbZ fcUnq gks rFkk S1, S
2'kkado dsukfHkd gks ] rc
(PS1+ PS
2) dk vf/kdre eku gksxk&
(A) .e (B) e. (C) .2 (D) e2Sol. e(x22 ex + e2) + .(y2 2.y + .2) = .e
/ 0 / 0e
yex22 .
!.
= 1 (a > b)
Ellipse a = . , b = e
Req. PS1+ PS
2= 2 .
7. Let f(x) =)axcos()axcos(
)axsin()axsin(
!"!!"
, then
(A) f(x + 2.) = f(x) but f(x + 1) -f(x) for any 0 < 1 < 2. (B) f is a strictly increasing function(C) f is strictly decreasing function (D) f is a constant function
;fn f(x) =)axcos()axcos(
)axsin()axsin(
!"!!"
, rc
(A) f(x + 2.) = f(x) ijUrq fdlh Hkh 0 < 1 < 2. ds fy, f(x + 1) -f(x)
(B) f vfuok;Zr% ,d o/kZeku Qyu gSA(C) f vfuok;Zr% ,d leku Qyu gSA
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
4/43
PAGE - 4
KVPY QUESTION PAPER - STREAM (SB / SX)
(D) f ,d fu;r Qyu gSA
Sol. f(x) =asinxsin2
acos.xsin2(x -n., n 2I)
= cot a(D) = constant function
8. The value of tan 813tan 633tan273+ tan93is
O;atd tan 813
tan 633
tan273+ tan93dk eku gS&(A) 0 (B) 2 (C) 3 (D) 4Sol. tan813tan633tan273+ tan93
cot93cot273tan273+ tan93(cot93+ tan93) (cot273+ tan 273)2 cosec1832 cosec543
2 $$%
&''(
)
!" 15
4
15
4
8 $%
&'(
)4
2
= 4Ans. (D)
9. The midpoint of the domain of the function f(x) = 5x24 !" for real x is
okLrfod x ds fy, Qyu f(x) = 5x24 !" ds izkUr dk e/; fcUnq gS&
(A)4
1(B)
2
3(C)
3
2(D)
5
2"
Sol. 4 5x2 ! 40, 2x + 5 40
0 #2x + 5 #16
5 #2x #11
2
5"#x #
2
11
* mid point is2
2
11
2
5!"
=2.2
6.=
2
3
Ans. (B)
10. Let n be a natural number and let a be a real number. The number of zeros of x2n+1(2n + 1) x + a = 0 in theinterval [1, 1] is(A) 2 if a > 0
(B) 2 if a < 0(C) at most one for every vale of a(D) at least three for every value of a
eku ysa fd n ,d izkdr la[;k gS rFkk a ,d okLrfod la[;k gSA lehdj.k x2n+1(2n + 1) x + a = 0 ds 'kwU;ksa dh la[;kvUrjky [1, 1] esa gS&(A) 2 ;fn a > 0(B) 2 ;fn a < 0(C) izR;sd a ds eku ds fy, vf/kd ls vf/kd ,d(D) izR;sd a ds eku ds fy, de ls de rhu
Sol. f(x) = x2n +1(2n + 1) x + af 5(x) = (2n + 1)(x2n1)
x =
1 6point of local maximax = 1 6point of local minima
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
5/43
PAGE - 5
KVPY QUESTION PAPER - STREAM (SB / SX)
graph of y = f(x) when a = 0
f(x) is decreasing on [1, 1]. Thus, f(x) will have atmost one root on [1,1] that too will happen if f(1) 40 andf(1) # 0 i.e. for a 2[2n, 2n]Answer (C)
11. Let f : R 6R be the function f(x) = (x a1) (x a
2) + (x a
2) (x a
3)+ (x x
3) (x x
1) with a
1, a
2, a
32 R. Then
f(x) 40 if and only if(A) at least two of a
1, a
2, a
3are equal (B) a
1= a
2= a
3
(C) a1, a
2, a
3are all distinct (D) a
1, a
2, a
3are all positive and distinct
;fn f : R 6R ,d Qyu f(x) = (x a1) (x a
2) + (x a
2) (x a
3)+ (x x
3) (x x
1) tgk a
1, a
2, a
32 R rc
f(x) 40 ;fn vkSj dsoy ;fn(A) a
1, a
2, a
3esa de ls de nks cjkcj gSA (B) a
1= a
2= a
3
(C) a1, a
2, a
3rhuksa fofHkUu gSA (D) a
1, a
2, a
3rhuksa /kukRed vkSj fofHkUu gSA
Sol. f(x) = 3x22(a1+ a2+ a3) x + a1a2+ a2a3+ a3a140* D #04(a
1+ a
2+ a
3)24.3.(a
1a
2+ a
2a
3+ a
3a
1) #0
21a +
22a +
23a a1a2a2a3a3a1#0
2
1[(a
1a
2)2+ (a
2a
3)2+ (a
3a
1)2] #0
* a1= a
2= a
3
Ans. (B)
12. The value
/ 2
2 1
0
/ 2
2 1
0
(sinx) dx
(sinx) dx
.
!
."
7
7is
/ 2
2 1
0
/ 2
2 1
0
(sinx) dx
(sin x) dx
.!
."
7
7dk eku gS&
(A)12
12!(B)
12
12
!
"(C)
2
12!(D) 22
Sol. I1= 7
. 2/
0
2)x(sin (sinx)1dx
I1=
2/
0
2)x)(sinx(cos.
$%&'
()" + 2
12
2/
0
2 )x(sin)x(cos ".
7 dx
I1= 2 $$%
&
''(
)
" 77.
!
.
" dxxsindx)x(sin
2/
0
12
2/
0
12
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
6/43
PAGE - 6
KVPY QUESTION PAPER - STREAM (SB / SX)
I1= 2 (I2I1) Here I1= 7
."
2/
0
12)x(sin dx
2
1
88
=)12(
2
! $
$%
&''(
)
"
"
)12(
12
= 22 " Ans.
13. The value 7 !!2012
2012
53 dx)1x)x(sin( is
7 !!2012
2012
53 dx)1x)x(sin( dk eku gS&
(A) 2012 (B) 2013 (C) 0 (D) 4024
Sol. 7 !
2012
2012
53 dx)xx(sin
+ 7
2012
2012
dx.1
= 0 + 2012 (2012)= 4024 Ans.
14. Let [x] and {x} be the integer part and fractional part of a real number x respectively. The value of the integral
75
0
dx}x{]x[ is
;fn [x] vkSj {x}, ,d okLrfod la[;k x ds e'k% iw.kkd rFkk fHkUukRed va'k gSA rc lekdy
7
5
0
dx}x{]x[ dk eku gksxk&
(A) 5/2 (B) 5 (C) 34.5 (D) 35.5
Sol. 75
0
dx}x]{x[
= dx}x{.0
1
0
7 + 72
1
dx}x{.1. + 73
2
dx}x{2 + 74
3
dx}x{3 + 75
4
dx}x{.4
= 0 + 1 71
0
dx.x + 2 7 !1
0
3dx.x 9 7 !1
0
4xdx .
7
1
0
xdx
= (1 + 2 + 3 + 4) 71
0
dx.x
= 10 .
1
0
2
2
x
::;
?
= 10 . $%
&'(
)" 0
2
1 = 5
Ans. (B)
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
7/43
PAGE - 7
KVPY QUESTION PAPER - STREAM (SB / SX)
15. Let Sn= @ A
n
1kk denote the sum of the first n positive integers. The numbers S
1, S
2, S
3, ....S
99are written
on 99 cards. The probability of drawing a cards with an even number written on it is
eku ysaSn= @ A
n
1kk izFke n /kukRed iw.kkdksads ;ks x dksfu:fir djrk gS A la[;k,aS
1, S
2, S
3,...S
99dks99 i=kksaij fy[kk
x;k gSA blesals ,d i=k ftlij le la[;k va fdr gks] ds [khapus dh izkf;drk gksxh&
(A) 2
1
(B) 100
49
(C) 99
49
(D) 99
48
Sol. Sn @
A
n
1k
K =/ 0
2
1nn !is even (n : 1, 2, ............. 99)
n = multiple of 44, 8, .......... 96Or (=) n is (multiple of 4 1)3, 7 ............... 99Total favourable cases 24 + 25 = 49
! P[E] =99
49Ans.
16. A purse contains 4 copper coins and 3 silver coins. A second purse contains 6 coins and 4 silver coins. Apurse is chosen randomly and a coin is taken out of it. What is the probability that it is a copper coin?
,d FkSyh esa4 rkacs vkSj 3 pkanh ds flDds gSA ,d nwljh FkSyh esa 6 rkacsvkSj 4 pkanh ds flDds gSA bu nks FkSfy;ksa esa ls ,dFkSyh ;knfPNd fudkyh tkrh gS vkSj mlesa ls ,d flDdk fudkyk tkrk gSA bl ckr dh izkf;drk D;k gS fd flDdk rkacsdk gS ?
(A)70
41(B)
70
31(C)
70
27(D)
3
1
Ans. (A)
Sol. req. prob = :
;
?!
10
6
7
4
2
1
=70
41
70
4240
2
1A
!9 Ans.
17. Let H be the orthocentre of an acuteangled triangle ABC and O be its circumcenter. Then HCHBHA !!
(A) is equal to HO (B) is equal to HO3
(C) is equal to HO2 (D) is not a scalar multiple of HO in general
;fn H ,d fuEudks.k f=kHkqt ABC dk yEc dsUnzgS ,oa O bldk ifjdsUnz gSA rc HCHBHA !!
(A) HO ds cjkcj gksxkA (B) HO3 ds cjkcj gksxkA
(C) HO2 dscjkcj gksxkA (D) lkekU;r% HO dk vfn'k xq.ku ugha gSA
Sol.
OH = cba"""
!!
HA = )cb( "" !
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
8/43
PAGE - 8
KVPY QUESTION PAPER - STREAM (SB / SX)
HB = )ac(""
!
HC = )ba(""
!
HCHBHA !! = 2( cba"""
!! )
= 2 OH = 2 HOAns. (C)
18. The number of ordered pairs (m,n) where m, n 2{1, 2, 3, ......, 50}, such that 6m+ 9nis a multiple of 5 isfer ;qXeksa (m,n) tgk m, n 2{1, 2, 3, ......, 50} bl izdkj gS fd 6m+ 9n, 5 dk xq.kt gSA bl izdkj ds fer ;qXeksadh la[;k gksxh&(A) 1250 (B) 2500 (C) 625 (D) 500
Sol. 6m + 9n
Unit digit of 6m is = 6Unit digit of 9nwill be = 9 or 1For multiple of 5 unit digit of 9nmust be = 9It occur when n = oddTotal number of ordered pair = 50 25 = 1250
19. Suppose a1
, a2
, a3
, ....., a2012
are integers arranged on a circle. Each number is equal to the average of itstwo adjacent numbers. If the sum of all even indeced numbers is 3018, what is the sum of all numbers?
eku ysafd iw.kkd a1, a
2, a
3, ....., a
2012dks,d o k ij lt;k x;k gSA izR;sd la[;k viuh fudVorhZnks la [;kvksadh vkSlr
gSA ;fn izR;sd le lwpd la[;k dk ;ksx 3018 gks] rks lHkh la[;kvksadk ;ksx D;k gks xk ?(A) 0 (B) 1509 (C) 3018 (D) 6036
Sol. a2=
2
aa 31!
a3=
2
aa 42!
a1=
2
aa 20122!
a2012
=2
aa 12011!
Now a2+ a
4+ ......... + a
2012= 3018 .................... (1)
2a2+ 2a
4+ .................... + 2a
2012= 6036
a1+ a
3+ a
3+ a
5+ .............. + a
2011+ a
1= 6036
2(a1+ a
3+ ................. + a
2011) = 6036
a1+ a
3+ ................ + a
2011= 3018 ..................... (2)
By adding (1) and (2) we geta
1+ a
2+ a
3+ ............ + a
2012= 6036
20. Let S = 1, 2, 3, ...., n} and A = {(a, b) | 1 #a, b #n} = S 9S . A subset B of A is said to be a good subset if
(x, x) 2B for every x 2S. Then the number of good subsets of A is;fn S = 1, 2, 3, ...., n} rFkk A = {(a, b) | 1 #a, b #n} = S 9S . A ds mileqPp; B dks vPNk mileqPp; rc dgktk,xk tc izR;sd x 2S ds fy, (x, x) 2B gksA rc A ds vPNs mileqPp;ksa dh la[;k gksxh&
(A) 1 (B) 2n (C) 2n(n1) (D)2n2
Sol. Number of element in B = n n = n2
Number of elements of type (x, x) = n
*after choosing n elements.We can choose any number of elements from remaining n2n elements.
*Number of subsets =nn
nn2
nn1
nn0
nn2
2222
C......CCC !!!
=nn22
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
9/43
PAGE - 9
KVPY QUESTION PAPER - STREAM (SB / SX)
PHYSICS
21. An ideal monatomic gas expands to twice its volume. If the process is isothermal, the magnitude of work
done by the gas is Wi. If the process is adiabatic the magnitude of work done by the gas is W
a. Which of
the following is true
,d ,dijek.kfod vkn'kZ xSl izlkfjr gksdj nks xquh vk;ru dh gks tkrh gSA ;fn izf;k lerkih; gS rks xSl }kjk fd;k
x;k dk;ZWi gSA ;fn izf;k :)ks"e gS rks xSl }kjk fd;k x;k dk;Z WagSA fuEufyf[kr esa dkSu lgh gS \
(A) Wi = Wa> 0 (B) W i> Wa> 0 (C) W i> Wa= 0 (D) Wa> Wi= 0
Sol.
Since area of PV graph under isothermal curve is greater than area under adiabatic curve
So, wi> wa > 0Ans. (B)
22. The capacitor of capacitance C in the circuit shown is fully charged initially, Resistance is R.
ifjiFk esa n'kkZ, C /kkfjrk dk ,d la/kkfj=k izkjEHk ls iw.kZ :i ls vkosf'kr gSA R frjks/k gSA
After the switch S is closed, the time taken to reduce the stored energy in the capacitor to half its initial value
is :
fLop (S) ds can gksus ds ckn la/kkfj=k esa lafpr tkZfdrus le; esa izkjfEHkd eku dh vk/kh gks tk;sxh\
(A)2
RC(B) RCln2 (C) 2RCln2 (D) 2
2lnRC
Sol. Q = Q0et/RC
2
Q0= Q
0et/RC
2
1= et/RC Ans. (D)
RC
t
2
1n "A#
2nRC
t#A
t = RC2
2n#
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
10/43
PAGE - 10
KVPY QUESTION PAPER - STREAM (SB / SX)
23. A liquid drop placed on a horizontal plane has a near spherical shape (slightly flattened due to gravity). Let R
be the radius of its largest horizontal section. A small disturbance causes the drop to vibrate with frequency
Babout its equilibrium shape. By dimensional analysis the ratio
3R
c
C
Dcan be (Here Dis surface tension,
Cis density, g is acceleration due to gravity, and k is an arbitrary dimensionless constant)
,d {kSfrt ry ij fLFkr nzo dh ,d cwan yxHkx xksykdkj vkfr dh gS xq:Rokd"kZ.k ds dkj.k cwan FkksM+h lh QSy tkrh gSxksys dslcls cM+s {kSfrt vuq LFk dh f=kT;k R gSA ,d NksVk fo{kksHk cwan dks blds lkE;koLFkk vkfr ds ifjr% vkofk B
ij daiu djkrk gSA foeh; fo'ys"k.k ls
3R
c
C
Dvuqikr fuEufyf[kr esa dkSulk gks ldrk gS\ ;gk Di"B ruko] C?kuRo]
g xq:Roh; Roj.k vkSj k ,d ;knPN foek jfgr fLFkjkad gSA
(A)D
C 2gRk(B)
DCg
Rk 3
(C)D
Cg
Rk 2
(D) DC
g
k
Sol. 3R/CD
B=
DC
B3R
=
2/1
2
331
MT
LMLT
::;
?"
""
= T1T
= 1
KR/ 3
ACD
B
2
3
2 KR ADCB
K2=2
3
TR "
DC
=2
2
RTR "
DC
K = gR2
DC
Ans. (A)
24. Seven identical coins are rigidly arranged on a flat table in the pattern shown below so that each coin touches
its neighbours. Each coin is a thin disc of mass m and radius r. Note that the moment of inertia of an
individual coin about an axis passing through center and perpendicular to the plane of the coin is2
mr 2.
,d {kSfrt est ij leku vkdkj dslkr flDds n
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
11/43
PAGE - 11
KVPY QUESTION PAPER - STREAM (SB / SX)
The moment of inertia of the system of seven coins about an axis that passes through the point P (the centre
of the coin positioned directly to the right of the central coin) and perpendicular to the plane of the coins is
n'kkZ, x,s fp=k esa bu lkrksa flDdksads lewg dk fcUnq P ls xqtjrs gq, ,oa flDdsds ya cor v{k ds lkis{k tM+Ro vk?kw.kZD;k
gksxk\ P dsUnzh; flDds ds nkfgus fLFkr flDds dk dsUnzgSA
(A)2
55mr2 (B)
2
127mr2 (C)
2
111mr2 (D) 55 mr2
Sol.
8P=
::;
?!!9
::;
?!!9
::;
?!! 2
22
22
22
)r4(m2
mr2)32r(m
2
mr3)r2(m
2
mr
2
mr
=2mr
2
111.
25. A planet orbits in an elliptical path of eccentricity e around a massive star considered fixed at one of the foci.
The point in space where it is closest to the star is denoted by P and the point where it is farthest is denoted
by A. Let vPand vAbe the respective speeds at P and A. Then
,d xzg mRdsUnzrk (eccentricity) 'e' okyh ,d nh?kZ okkdkj d{k esa,d fo'kky rkjs dk pDdj yxkrk gSA fo'kky rkjk nh?kZ
ok ds,d ukfHk ij fLFkj gSA rkjs ds lcls utnhd ds fcUnq dks P ,oa lcls nwj dsfcUnq dks A.ls n'kkZ;k x;k gSA ;fn vP,oavA e'k% P vkSj A ij xzg dk osx gSrks
(A) e1
e1
v
v
A
P
"!
A (B)A
P
v
v= 1 (C)
e1
e1
v
v 2
A
P
"!
A (D) 2
2
A
P
e1
e1
v
v
"
!A
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
12/43
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
13/43
PAGE - 13
KVPY QUESTION PAPER - STREAM (SB / SX)
Sol.
B0=
:;
? .!
...
E
nsin
nsin
n
cosR
i
40
B0=
ntan
R
i
2
0 ..
E
Ans. (A)
28. A conducting rod of mass m and length # is free to move without friction on two parallel long conducting rails,
as shown below. There is a resistance R acorss the the rails. In the entire space around, there is a uniform
magnetic filed B normal to the plane of the rod and rails. The rod is given an impulsive velocity v0.
n'kkZ, x, fp=k esa ,d m nzO;eku vkSj LyackbZ dh pkyd NM nks yach vkSj lekUrj pkyd iVfj;ksa ij fcuk ?k"kZ.k ds xfr
dj ldrh gSA iVfj;ksa ds chp dk izfrjks/k R gSA fp=k dh lrg ds yacor~] gj txg ,d leku pqEcdh; {ks=k B gSA NM dks
vpkud ,d v0 ifjek.k dk vkosxh osx iznku fd;k tkrk gSA
Finally, the initial energy2
1mv0
2
(A) will be converted fully into heat energy in the resistor
(B) will enable rod to continue to move eith velocity v0since the rails are frictionless
(C) will be converted fully into magnetic energy due to induced current
(D) will be converted into the work done against the magnetic field
vUrr% izkjafHkd tkZ2
1mv
02
(A) iw.kZ :i lsizfrjks/k R esa "eh; tkZ esa :ikUrfjr gks tk,xhA
(B) NM+ dks v0xfr ls xfreku j[ksxh D;ksafd NM+,oa iVfj;ksa ds chp ?k"kZ.k ugha gSA
(C) mRizsfjr fo|qr /kkjk dh otg ls] iw.kZr;k pqEcdh; tkZ esa :ikUrfjr gks tk,xhA(D) pqEcdh; {ks=k ds f[kykQ dk;Z djus esaO;; gks tk,xhA
Sol. Due to the negative work on rod K.E. will decrease and finally become zero.Ans. (A)
29. A steady current 8flows through a wire of radius r, length L and resistivity C. The current produces heat in thewire. The rate of heat loss in a wire is proportional its surface area. The steady temperature of the wire is
independent of
,d r f=kT;k] L yackbZ ,oa Cizfrjks/kdrk ds rkj esa LFkk;h fo|qr /kkjk I izokfgr gksrh gSA /kkjk dh otg ls rkj esa "ek dk
fuekZ.k gksrk gSA rkj esa "ek ds {k; dh nj rkj ds lrgh {ks=kQy ds vuqikrh gSA rkj dk fLFkj rkieku fuEu esa ls fdlds
ij fuHkZj ugha gS\(A) L (B) r (C) 8 (D) C
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
14/43
PAGE - 14
KVPY QUESTION PAPER - STREAM (SB / SX)
Sol. R =A
#C
R = 2r
L
.
C
82R = K2.rLdt
dT
2
2
r
L
.
C8= K2.rL
dt
dT
dt
dT= 32
2
r2K
L
.
C8Ans. (A)
30. The ratio of the speed of sound to the average speed of an air molecule at 300K and 1 atmospheric pressure
is close to
300K rkieku ,oa1 atm nkc ij /ofu dh xfr vkSj ok;q ds,d v.kq dh vkSlr xfr dk vuqikr fuEu esa lsfdlds fudV
gS \
(A) 1 (B) 300 (C) 300
1(D) 300
Sol.
m
RT8
m
RT
.
C
=85
7.= 0.73
So, closest ans is 1.Ans. (A)
31. In one model of the election, tho electron of mass meis thought to be a uniformly charged shell of radius Rand total charge e, whose electrostatic energy E is equivalent to its mass mevia Einstein's mass energy
relation E = mec2 . In this model, R is approximately (me = 9.1 10
31 kg, c = 3 108 m.s1,
04
1
.F = 9 109 Farads m1, magnitude of the electron charge = 1.6 1019C)
bysDVkWu ds ,d fu:i.k esa menzO;eku ds bysDVkWu dks R f=kT;k ds leku :i ls vkosf'kr ,d xksyk] ftldk dqy vkos'k
e, gS] le>k tkrk gSA bl vkosf'kr xksys dh fLFkj oS|qr tkZ E ,oa nzO;eku mevkbaLVhu ds E = mec2.laca/k ls nh tkrh
g SA bl fu:i.k e s a R dk eku fdlds djhc g S\ (m e = 9.1 1031 kg, c = 3 108 m.s1,
04
1
.F = 9 109 Farads m1, bysDVkWu dk vkos'k = 1.6 1019C)
(A) 1.4 1015m (B) 2 1013m (C) 5.3 1011m (D) 2.8 1035mSol. U = mc2
22
mcR2
KQA
R2
)106.1(109 2199 "999= 9.1 1031 (3 108)2
R = 2831
2199
)103(101.92
)106.1(109
9999
999"
"
= 1.4 10
15
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
15/43
PAGE - 15
KVPY QUESTION PAPER - STREAM (SB / SX)
Ans. (A)
32. A body is executing simple harmonic motion of amplitude a and period T about the equilibrium position
x = 0. Large numbers of snapshots are taken at random of this body in motion. The probability of the body
being found in a very small interval x to x + |dx| is highest at
vius lkE; voLFkk x = 0. dslkis{k ,d fiM+ a vk;ke vkSj T vkorZ dky ls ljy vkorZ xfr (simple harmonic
morion) djrk gSA bl oLrqdh ;knfPNd xfr ds dbZ lkj s QksVk s fp=k snapshots [khpsa tkrs gSA x vkSj x + |dx| ds
chp NksVs varjky dsa fiaM ds ik, tkus dh lclsT;knk izkf;drk dgk gksxh\
(A) x = a (B) x = 0 (C) x = a/2 (D) x = 2
a
Sol. Probability of being found is maximum where speed is minimum.So, x = aAns. (A)
33. Two identical bodies are made of a material for which the heat capacity increases with temperature One of
these is held at a temperature of 100C while the other one is kept at 0C. If the two are brought into contact,then, assuming no heat loss to the environment, the final temperature that they will reach is
nks ,d & tSls fiaM ,d ,slsinkFkZ ls cuk, tkrs gS ftudh "ek & /kkfjrk rkieku ds lkFk c
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
16/43
PAGE - 16
KVPY QUESTION PAPER - STREAM (SB / SX)
36. A ball of mass m suspended from a rigid support by an inextensible massless string is released from a
height h above its lowest point. At its lowest point it colIides elastically with a block of mass 2m at rest on a
frictionless surface. Neglect the dimensions of the ball and the block. After the collision the ball rises to a
maximum height of
,d
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
17/43
PAGE - 17
KVPY QUESTION PAPER - STREAM (SB / SX)
(A) (B)
(C) (D)
Sol. Let ball is moving with speedv at anytime t hence
Hence, mdt
dv= mg Kv2
On the basis of equation we can rays that speed first increase and become constant when mg = kv2
Hence, Ans. (A)
38. A cylindrical steel rod of length 0.10m and thermal conductivity 50 W.m1.K1is welded end to end to copper
rod of thermal conductivity 400 W.m1.K1and of the same area of cross section but 0.20 m long. The free
end of the steel rod is maintained at 100C and that of the copper rod at 0C. Assuming that the rods areperfectly insulated from the surrounding the temperature at the junction of the two rods is
LVhy dh ,d csyukdkj NM+ ftldh yackbZ 0.10m rFkk "eh; pkydrk 50 W.m1.K1gS] ,d Nksj ij leku vuqizLFk
dkV ,oa0.20m yach ,d nwljh csyukdkj NM+ftldh "eh; pkydrk 400 W.m1.K1gS] ls tqMh gSA LVhy NM+ds [kqys
fljs dks 100C ,oa rkcsadh NM+ ds [kq ys fljs dks 0C.rkieku ij fLFkj j[kk x;k gSA ;g ekurs gq, fd NMksa ls ifjos'k esa
"ek dk kl ughagks jgk gS ] NMksa ds tksM+ ij rkieku D;k gksxk\(A) 20C (B) 30C (C) 40C (D) 50C
Sol. Resistance of steel =A50
1.0
9=
A500
1
Resistance of copper =A400
2.0=
A200
1
Both are connected in series hence heat current in both will be same. So
$%
&'(
)
"
A500
1
T100 =
$
%
&'
(
)
"
A2000
1
0T, T = 20C
Ans. (A)
39. A parent nucleus X is decaying into daughter nucleus Y which in turn decays to Z. The half lives of X and Y
are 4000 years and 20 years respectively. In a certain sample, it is found that the number of Y nuclei hardly
changes with time. If the number of X nuclei in the sample is 4 1020, the number of Y nuclei present in itis
,d ewy ukfHkd X nwljsukfHkd Y esa {kf;r gksrk gS] tks fQj Z. esa {kf;r gksrk gSA X vkSj Y dh v/kZvk;q e'k% 4000 o"kZ
,oa 20 o"kZ gSA ,d uewus esa;g ns[kk x;k gS fd Y ukfHkdksa dh la[;k esa le; ds lkFk dksbZ [kkl ifjorZu ughagks jgk gSA
;fn bl uewus esa X ukfHkdksa dh la[;k 4 1020rks ml le; Y ukfHkdksa dh la[;k D;k gksxh\(A) 2 1017 (B) 2 1020 (C) 4 1023 (D) 4 1020
Sol. FromN
1J
1= N
2J
2
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
18/43
PAGE - 18
KVPY QUESTION PAPER - STREAM (SB / SX)
4 1020=40000
)2(n#=
20
)2(nN2
#
, N2= 2 107
Ans. (A)
40. An unpolarized beam of light of intensity 80passes through two linear polarizers making an angle of 30 withrespect to each other. The emergent beam will have an intensity.
nks js[kh; /kqzodksa ds chp] tks ijLij 30 ij fLFkj gS ,d 80rhozrk dh v/kzqfor izdk'k fdj.k xqtjrh gSA ckgj vkus okyhfdj.k dh rhozrk D;k gksxh\
(A)4
3 08(B)
4
3 08 (C)8
3 08(D)
808
Sol.
$%&'
()8A$
%&'
()8
4
3
230cos
2
020
Final intensity will be =8
3 08
Ans. (C)
CHEMISTRY41. Among the following, the species with the highest bond order is :
fuEufyf[kr esa fdldk vf/kdre vkcU/k e (bond order) gS \
(A) O2 (B) F2 (C) O2+ (D) F2
Ans. (C)Sol. According to MOT bond order of O
2, F
2, O
2+and F
2is respectively 2, 1, 2.5 and 0.5.
gy MOT dsvuqlkj O2, F
2, O
2+rFkk F
2dk ca/k e e'k% 2, 1, 2.5 o 0.5 gSA
42. The molecule with non-zero dipole moment is :
v.kq ftldk f}/kzqo vk?kw.kZ (dipole moment) v'kwU; gS \(A) BCl
3(B) BeCl
2(C) CCl
4(D) NCl
3
Ans. (D)Sol. BCl
3, BeCl
2and CCl
4has zero dipole moment due to symmetric structure where as shape of NCl
3is pyrami-
dal due to presence of lone pair.
gy BCl3, BeCl
2o CCl
4dk f}/kzqo vk?kw.kZ'kwU; gksrk gSD;ksafd budh lefer lajpuk gksrh gS] tcfd NCl
3dh vkfr fijsfefM;y
gksrh gSD;ksafd blesa ,dkdh bysDVkWu ;qXe mifLFkr gksrk gS A
43. For a one-electron atom, the set of allowed quantum numbers is :
,d&bysDVkWu ijek.kqds fy, vuq er DokaVe la[;k,(allowed quantum numbers) gS \
(A) n = 1, # = 0, #m = 0, ms= + (B) n = 1, # = 1, #m = 0, ms= +
(C) n = 1, # = 0, #m = 1, ms= (D) n = 1, # = 1, #m = 1, ms=
Ans. (A)Sol. The value of n > # and m should have values from # to + # .
n dk eku > # o m ds eku # ls + # rd gksus pkfg,A .
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
19/43
PAGE - 19
KVPY QUESTION PAPER - STREAM (SB / SX)
44. In the reaction of benzene with an electrophile E+, the structure of the intermediate D-complex can berepresented as :
csathu dh ,d bysDVkWuLusgh (electrophile) E+dslkFk vfHkf;k esa e/;orhzD-ladj dh lajpuk dksbl izdkj iznf'kZ r djldrsgSa \
(A) (B) (C) (D)
Ans. Option DClosest, if () is change to #$fodYi Dlgh gS] D;ksafd () dks #%esa ifjofrZr fd;k tk ldrk gSA
Sol.
45. The most stable conformation of 2, 3-dibromobutane is :
2, 3-MkbczkseksC;wVsu dk vf/kdre LFkk;h la:i.k D;k gS \
(A) (B) (C) (D)
Ans. (Bonus)
46. Typical electronic energy gaps in molecules are about 1.0 eV. In terms of temperature, the gap is closest to:
v.kqvksads bysDVkWfud tkZ&varjky (energy gaps)dk eku yxHkx 1.0 eV gSA rkieku dslanHkZesa;g va rj buesals fdldsfudV gS \(A) 102K (B) 104K (C) 103K (D) 105K
Ans. (B)Sol. KE = | T.E. |
* G(KE) = G(T.E.)
2
3 8.3 (GT) = 1.6 1019 6 1023
(GT) =3.8
106.9 49
3
2
(GT) = 7.6 103K i.e. close to 104K.(GT) = 7.6 103K vFkkZr 104K ds fudV gSA
47. The major final product in the following reaction is :
fuEu vfHkf;k dk eq[; vafre mRikn D;k gS \
CH3CH
2CN
!KKKKK 6K
OH)2
MgBrCH)1
3
3
(A) (B)
(C) (D)
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
20/43
PAGE - 20
KVPY QUESTION PAPER - STREAM (SB / SX)
Ans. (C)
Sol.
48. A zero-order reaction, A 6Product, with an initial concentration [A]0has a half-life of 0.2 s. If one starts with
the concentration 2[A]0, then the half-life is :
,d 'kwU; dksfV vfHkf;k] A 6mRikn (product), dh v)Z&vk;q 0.2 s gS] tc izkFkfed lkanzrk [A]0gSA ;fn vfHkf;k
2[A]0dh lkUnzrk ls 'kq: gksrh rks bldh v)Z vk;q D;k gksxh \
(A) 0.1 s (B) 0.4 s (C) 0.2 s (D) 0.8 sAns. (B)Sol. t
1/2L(a)1 n
II
I
)t(
)t(
2/1
2/1=
01
2
1
a
a "
$$%
&''(
)
II)t(
2.0
2/1=
0
0
A2
A
(t1/2
)II= 0.4 s
49. The isoelectronic pair of ions is :
fuEu vk;fud ;qXe lebysDVkWfud (isoelectronic) gS %(A) Sc2+and V3+ (B) Mn3+and Fe2+ (C) Mn2+and Fe3+ (D) Ni3+and Fe2+
Ans. (C)Sol.
25Mn2+and
26Fe3+both has 23 electrons.
25Mn2+o
26Fe3+nksuksa esa23 bysDVkWu gSA
50. The major product in the following reaction is :
fuEu vfHkf;k dk eq[; mRikn D;k gS \
KKKK 6K 2NaNH
(A) (B) (C) (D)
Ans. (A)
Sol.
51. The major product of the following reaction is :
fuEu vfHkf;k dk eq[; mRikn D;k gS \
KKKKK 6K HBr.Conc
(A) (B) (C) (D)
Ans. (B)
Sol.
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
21/43
PAGE - 21
KVPY QUESTION PAPER - STREAM (SB / SX)
52. The oxidation state of cobalt in the following molecule is :
fuEufyf[kr v.kq esa dksckYV dh vkWDlhdj.k voLFkk (oxidation state) D;k gS\
(A) 3 (B) 1 (C) 2 (D) 0Ans. (D)Sol. In metal carbonyls oxidation state of metal is equal to zero.
/kkrq dkcksZfuy esa /kkrq dh vkWDlhdj.k voLFkk 'kwU; ds cjkcj gksrh gSA
53. The pKaof a weak acid is 5.85. The concentrations of the acid and its conjugate base are equal at a pH of:
,d nqcZy vEy ds pKadk eku 5.85 gSA pH dsfdl eku ds fy, vEy dh vkSj blds la ;qXe (conjugate) {kkj dh lkUnzrk
leku gksxh \(A) 6.85 (B) 5.85 (C) 4.85 (D) 7.85
Ans. (B)Sol. At pH = pK
athe concenteration of acid and its conjugate base are equal.
pH = pKaij vEy o blds l;qfXer {kkj dh lkUnzrk cjkcj gksrh gSA
54. For a tetrahedral complex [MCl4]2, the spin-only magnetic moment is 3.83 BM. The element M is :
prq"Qydh; ladqy (tetrahedral complex) [MCl4]2ds fy, dsoy izp.k pqEcdh; vk?kw.kZ (spin-only magnetic
moment) 3.83 BM gSA rRo M D;k gS \(A) Co (B) Cu (C) Mn (D) Fe
Ans. (A)Sol. It is high spin complex as Clis weak field effect ligand. In [CoCl
4]2oxidation state of Co is +2 in which 3
unpaired electrons are present which gives the spin-only magnetic moment equal to 3.83 BM.
;g mPp p.k ladqy gS D;ksafd Cl,d nqcZy {ks=k fyxs.M gSA [CoCl4]2esa Co dh vkWDlhdj.k voLFkk +2 gSA blesa rhu
v;qfXer bysDVkWu mifLFkr gS tks fd 3.83 BM ds cjkcj dsoy p.k pqEcdh; vk?kw.kZ n'kkZrs gSaA
55. Among the following graphs showing variation of rate (k) with temperature (T) for a reaction, the one thatexhibits Arrhenius behavior over the entire temperature range is :
fuEu vkjs[k esavfHkf;k nj ds ifjorZ u (k)dksrkieku (T) dslkFk n'kkZ ;k x;k gSA iwjsrki ifjlj esavkgsZfu;l (Arrhenius)O;ogkj dks buesa lsfdl vkjs[k }kjk n'kkZ;k x;k gS \
(A) (B) (C) (D)
Ans. (D)
Sol. K = RT/E aAe
ln K =RT
E a+ ln AA
56. The reaction that gives the following molecule as the major product is
fuEufyf[kr v.kq fdl vfHkf;k dk eq[; mRikn gS \
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
22/43
PAGE - 22
KVPY QUESTION PAPER - STREAM (SB / SX)
(A) (B)
(C) (D)
Ans. (B)
Sol.
57. The CO bond length in CO, CO2and CO
32follows the order :
CO, CO2vkSj CO
32esaCO vkca/k dh yEckbZ dk e D;k gS \
(A) CO < CO2< CO
32 (B) CO
2< CO
32< CO (C) CO > CO
2> CO
32 (D) CO
32< CO
2< CO
Ans. (A)
Sol. Greater is the bond order shorter will be bond length. In CO32
bond order in between 1 and 2, bond order ofCO
2is 2 where as bond order for CO is in between 2 and 3.
gy ftldk ca/k e vf/kd gksxk mldh ca/k yEckbZ de gksxhA CO32esa ca/k e 1 o 2 ds e/; gS] CO
2dk ca/k e 2 gS tcfd
CO dk ca/k e 2 o 3 ds e/; gSA
58. The equilibrium constant for the following reactions are K1and K
2, respectively.
2P(g) + 3Cl2(g) 2PCl
3(g)
PCl3(g) + Cl
2(g) PCl
5(g)
The the equilibrium constant for the reaction
2P(g) + 5Cl2(g) 2PCl
5(g)
is :
fuEufyf[kr vfHkf;kvksa ds fy, lkE; fLFkjkad e'k% K1rFkk K2gSA2P(g) + 3Cl
2(g) 2PCl
3(g)
PCl3(g) + Cl
2(g) PCl
5(g)
rc 2P(g) + 5Cl2(g) 2PCl
5(g) vfHkf;k ds fy, lkE; fLFkjkad D;k gksxk \
(A) K1K
2(B) K
1K
22 (C) K
12K
22 (D) K
12K
2
Ans. (B)
Sol. 2P(g) + 3Cl2(g) 2PCl
3(g) ........(i)
PCl3(g) + Cl
2(g) PCl
5(g) ........(ii)
2P(g) + 5Cl2(g) 2PCl
5(g) ........(iii)
On multipling equation (ii) by 2 and adding in (i) we obtain equation (iii)
Therefore, K3= K1K22lehdj.k (ii) dks 2 ls xq.kk dj lehdj.k (i) esa tksM+us ij gesa lehdj.k (iii) izkIr gksrh gSAblfy,, K
3= K
1K
22
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
23/43
PAGE - 23
KVPY QUESTION PAPER - STREAM (SB / SX)
59. The major product of the following reaction is :
fuEufyf[kr vfHkf;k dk eq[; mRikn D;k gS \
+ (CH3C)
2CHCH
2Cl KKK 6K 3
AlCl
(A) (B)
(C) (D)
Ans. (A)
Sol. The reagent given the question has an addition Cwithin bracket.
fn;s x;s iz'u ds vfHkdeZd ds czsdsV esa ,d vfrfjDr Cfn;k x;k gSA(CH
3)2CHCH
2Cl + AlCl
3K6 (CH
3)
2CHCH
2Cl - - - - AlCl
3K6(CH
3)
2CHCH
2++ AlCl
4
(CH3)2CHCH
2+ KKKKKK 6K " shifftingH2,1
(CH
3)3C+
60. Doping silicon with boron produces a :(A) n-type semiconductor (B) metallic conductor(C) p-type semiconductor (D) insulator
flfydu ds cksjkWu vifeJ.k (Doping) ls dkSu&lk mRikn curk gS \
(A) n-izdkj ds v)Zpkyd (B) /kkfRod pkyd(C) p-izdkj dsv)Zpkyd (D) fo|qr jks/kh
Ans. (C)Sol. As boron is trivalent impurity it will proudce p-type semiconductor.
D;ksafd cksjksu f=kla;ksth v'kqf) gS;g p-izdkj ds v)Zpkyd cukrk gSA
BIOLOGY61. The disorders that arise when the immune system destroys 'self' cells are called autoimmmune disorders.
Which of the following would be classified under this(A) rheumatoid arthritis (B) asthma (C) rhintis (D) eczema
Ans (A)
ftl fodkj jksx ds dkj.k izfrj{kd ra=k (immune system)viuh gh dksf'kdkvksa dk fouk'k djrk gS] mls vkReizfrj{kdjksx dgrs gSA fuEufyf[kr esa lsdkSu lk ,d jksx dgrs gSA fuEufyf[kr esa ls dkSulk ,d ,slk jksx gSA(A) xfB;k laf/k'kksFk (rheumatoid archritis) (B) nek (asthma)(C) uklk & 'kksFk (rhintis) (D) Nktu (eczema)
Ans (A)
62. Which of the following class of immunoglobulins can trigger the complement cascade ?(A) IgA (B) IgM (C) IgD (D) IgE
Ans (A)
dkWfIyesUV dSLdsM dks buesa ls dkSu lk bEequksXykscqyhu (immunoglobulins) izofrZr djrk gS\
(A) IgA (B) IgM (C) IgD (D) IgEAns (A)
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
24/43
PAGE - 24
KVPY QUESTION PAPER - STREAM (SB / SX)
63. Diabetes insipidus is due to(A) hypersecretion of vasoperssin(B) Hyposecretion of insulin(C) hypersecretion of insulin(D) hyposecretion of vasopressin
Ans (D)
MkbfCkVht buflfiMl (Diabetes insipidus) dk dkj.k D;k gS\(A) oSlksxzsflu dk vf/kd ek=kk esa lzo.k gksukA (B) bUL;wyhu dk lzo.k de gksukA
(C) bUL;wyhu dk vf/kd ek=kk esa lzo.k gksukA (D) oSlksizsflu dk lzo.k de gksukAAns (D)
64. Fossils are most often found in which kind of rocks ?(A) meteorites (B) sedimentary rocks(C) igneous rocks (D) metamorphic rocks
Ans (B)
fdl izdkj dh f'kykvksa esa T;knkrj thok'e ik, tkrs gS\(A) mYdkfi.M (meteorites) (B) volknh 'kSy (sedimentary rocks)(C) vkXus; 'kSy (igneous rocks) (D) dk;krj.kh 'kSy (metamorphic rocks)
Ans (B)
65. Peptic ulcers are caused by(A) a fungus, Candida albicans(B) a virus, cytomegalo virus(C) a parasite, Trypanosoma brucei(D) a bacterium, Helicobacter pylori
Ans (D)
isV ds oz.k (Peptic ulcers) fdl tho ds dkj.k gksrs gS\(A) ,d dodh] (Candida albicans) (B) ,d ok;jl (cytomegalo virus)(C) ,d ijtho] (Trypanosoma bruci) (D) ,d thok.kq(Helicobacter pylori)
Ans (D)
66. Transfer RNA (tRNA)(A) is present in the ribosomes and provides structural integrity(B) usually has clover leaf-like structure(C) carries genetic information from DNA to ribosomes(D) codes for proteins
Ans (B)
VkUlQj (tRNA)(A) jkbckslkse esafLFkr gS vkSj lajpukRed v[kaMrk nsrk gSA(B) lkekU;r% frifr;k (clover leaf-like) vkdkj dh gksrh gSA(C) DNA lsjkbckslkse rFkk vkuqoaf'kd lwpuk igqapkrk gSA(D) izksVhu cukrk gS
Ans (B)
67. Some animals excrete uric acid in urine (uricotelic) as it requires very little water. This is an adaptation toconserve water loss. Which animals among the following are most likely to be uricotelic?(A) fishes (B) amphibians (C) birds (D) mammals
Ans (C)
ew=k esa;wfjd vEy folftZr djus okysiz k.kh dks ;wfjdksVsfyd dgrs gSA ;g izf;k ikuh ds laj{k.k dsfy, vuqdwy gSA buesals dkSu lk izk.kh ;wfjdksVsfyd gS\(A) eNfy;k (B) i{kh (C) mHk;pj (D) Lru/kkjh
Ans (C)
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
25/43
PAGE - 25
KVPY QUESTION PAPER - STREAM (SB / SX)
68. A ripe mango, kept with unripe mangoes causes their ripening. This is due to the release of a gaseous planthormone(A) auxin (B) gibberlin (C) cytokinine (D) ethylene
Ans (D)
,d ids vke dks dPpsvkeksa ds lkFk j[kus ls dPPks vke idus 'kq: gks tkrs gSA ;g fdl xS lh; ikni gkeksZu ds fudyusdk dkj.k gS\(A) vkDlhu (B)lkbVksdkbuhu (C) ftCcjyhau (D) ,Fkhyhu
Ans (D)
69. Human chromosomes undergo structural changes during the cell cycle. Chromosomal structure can be bestvisualized if a chromosome is isolated from a cell at(A) G1 phase (B) S phase (C) G2 phase (D) M phase
Ans (D)
euq"; ds dksf'kdk p ds nkSjku ksekslkse dh lajpuk esa cnyko gksrk gSA bl cnyko dks Li"V :i ls ns[kus ds fy, pdh fdl izkoLFkk esa ksekslkse dk ijh{k.k fd;k tkuk pkfg,\(A) G1 izkoLFkk (B) S izkoLFkk (C) G2 izkoLFkk (D) M izkoLFkk
Ans (D)
70. By which of the following mechanisms is glucose reabsorbed from the glomerular filtrate by the kidney tubule(A) osmosis (B) diffusion (C) active transport (D) passiver transport
Ans (C)
fuEufyf[kr fdl izf;k ds }kjk xqnsZ ds fuL;aan }kjk Xykses:yj fQYVsV ls Xyqdkst iqu% 'kksf"kr gksrk gS\(A) ijklj.k (osmosis) (B) folj.k (diffusion)(C) lf; xeu (active transport) (D) fuf"; vfHkxeu (passiver transport)
Ans (C)
71. In mammals, the hormones secreted by the pituitary, the master gland, is itself regulated by(A) Hypothalamus (B) median cortex (C) pineal gland (D) cerebrum
Ans (A)
efLr"d ds fdl Hkkx }kjk Lru/kkjh ih;w"k ( pituitary gland) ds gkeksZu dk lzo.k & fu;a=k.k gksrk gSA(A) v/k'psrd (Hypothalamus) (B) ehfM;u dkVsZDl (median cortex)(C) ihfu;e xzfUFk (pineal gland) (D) izefLr"d (cerebrum)
Ans (A)
72. Which of the following is true for TCA cycle in eukaryotes(A) takes place in mitochondrion(B) produces no ATP(C) takes place in Golgi complex(D) independent of electron transport chain
Ans (A)
;wdSfj;ksV ds TCA p ds ckjs esa fuEufyf[kr dkSu lk dFku lgh gS\
(A) ekbVksdkfUM;k esa gksrk gSA (B) ATP ugha cukrkA(C) xkWYth dkEIysDl esa gksrk gSA (D) izefLr"d (cerebrum)
Ans (A)
73. A hormone molecule binds to a specific protein on the plasma membrane inducing a signal. The protein itbinds to it called(A) ligand (B) antibody (C) receptor (D) histone
Ans (C)
dksf'kdk f>Yyh ij fLFkr ml izksVhu dks D;k dgrs gS tks gkeksZu ls tqMrk gS vkSj ladsr izsfjr djrk gS\(A) layXuh (ligand) (B) xzkgh (receptor) (C) izfrj{kh (antibody) (D)fgLVksu (histone)
Ans (C)
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
26/43
PAGE - 26
KVPY QUESTION PAPER - STREAM (SB / SX)
74. DNA mutations that do not cause my functional change in the protein product are known as(A) nonsense mutations (B) missense mutations (C) deletion mutations (D) silent mutations
Ans (D)
DNA esa mRifjorZu] tks izksVhu ds izdk;Z esa cnyko ugha ykrs] mUgsa D;k dgrs gSa\(A) vuFkZd mRifjorZu (nonsense mutations) (B) vikFkZd mRifjorZu (missense mutations)(C) foyksih mRifjorZu (deletion mutations) (D) uhjo mRifjorZu (silent mutations)
Ans (D)
75. Plant roots are usually devoid of chlorophyll and cannot perform photosynthesis. However, three are excep-tions. Which of the following plant root can perform photosynthesis(A) Arabidopsis (B) Tinospora (C) Rice (D) Hibiscus
Ans (B)
ikS/kksadh tM+ esa DyksjksfQy ugha gksrk gS] ftlds dkj.k os izdk'k la'ys"k.k (photosynthesis)ugha dj ikrsA buesals dkSulk vlk/kkj.k foijhr mnkgj.k gS\(A) vjschMkIlhl (Arabidopsis) (B) VhuksLiksjk (Tinospora)(C) pkoy (Rice) (D) fgfcLdl (Hibiscus)
Ans (B)
76. Vitamin A deficiency leads to night-blindness. Which of the following is the reason for the disease ?
(A) rod cells are not converted to cone cells(B) rhodopsin pigment of rod cells is defective(C) melanin pigment is not synthesized in cone cells(D) cornea of eye gets dried
Ans (B)
foVkfeu , dh deh ls jrkSa/kh (night-blindness) gksrh gSA bldk dkj.k D;k gS\(A) 'kykdk dksf'kdkvksa (rod cells)dk 'kadq dksf'kdkvksas (cone cells) esa ifjofrZr ugha gksukA(B) 'kykdk dksf'kdkvksads jksMkW fIlu o.kZd dk (pigment) dk nks"kiw.kZ gksukA(C) 'kadq dksf'kdk esa esykuhu o.kZd dk ugha cuukA(D) vka[kksa ds LoPN eaMy (cornea) dk lw[k tkukA
Ans (B)
77. In Dengue virus infection, patients often develop haemorrhagic fever due to internal bleeding. This happensdue to the reduction of(A) platelets (B) RBCs (C) WBCs (D) lymphocytes
Ans (A)
MsUX;q ok;jl ds lae.k ls dbZjksfx;ksa esa vkUrfjd jDrlzko gksrk gS A buesa ls fdl dksf'kdk ds de gksus ls ,slk gksrk gS\(A) jDr foEck.kq (platelets) (B) yky :f/kj df.kdk (RBCs)(C) lQsn :f/kj df.kdk (WBCs) (D) ylhdk.kq(lymphocytes)
Ans (A)
78. If the sequence of bases in sense strand of DNA is 5'-GTTCATCG-3, then the sequence ofd bases in its RNAtranscript would be(A) 5'-GTTCATCG-3' (B) 5'GUUCAUCG-3 (C) 5'CAAGTAGC-3' (D) 5'CAAGUAGC -3
Ans (B)
vxj DNAdssence strand dk vuqe, 5'-GTTCATCG-3, 5'-GTTCATCG-3 5'-GTTCATCG-3 gS] rksmlds RNAdh izfrfyfi (transcript) dk vuqe D;k gksxk\(A) 5'-GTTCATCG-3' (B) 5'GUUCAUCG-3 (C) 5'CAAGTAGC-3' (D) 5'CAAGUAGC -3
Ans (B)
79. A refilex aciton is a quick involuntary response to stimulus. Which of the following is an example of BOTH,unconditioned and conditioned reflex(A) knee jerk reflex(B) secretion of saliva in response to the aroma of food(C) sneezing reflex(D) contration of the pupil in response to bright light
Ans (A)
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
27/43
PAGE - 27
KVPY QUESTION PAPER - STREAM (SB / SX)
fdlh mhiu ds vuSfPNd vuqf;k dks izfrorhZ f;k dgrs gSA buesa ls dkSu lk mnkgj.k vizkuqdwyh vkSj izkuqdwyh izfrorhZf;k, gS\(A) uh&tdZ (knee jerk) izfrorhZ (B) [kkus dh [kq'kcq ls eaqg esa ikuh vkuk(C) Nhad izfrorhZ (D) pedhys izdk'k esa iqrfy;ksa dk fldqMUkk
Ans (A)
80. In a food chain such as grass 6 deer 6lion, the energy cost of respiration as a proportion of total assimi-lated energy at each level would be(A) 60%- 30%-20% (B) 20%- 30%-60% (C) 20%- 60%-30% (D) 30%- 30%-30%
Ans (B)
?kkl & fgj.k & 'ksj] fd vkgkj Ja[kyk esa dqy laxzghr tkZ ds vuqikr esa izR;sd Lrj ij 'olu tkZ dh ykxr fdruhgksaxh\(A) 60%- 30%-20% (B) 20%- 30%-60% (C) 20%- 60%-30% (D) 30%- 30%-30%
Ans (B)
PART-IITwo Mark Questions
MATHEMATICS81. Suppose a, b, c are real numbers, and each of the equations x2+ 2ax + b2= 0 and x2+ 2bx + c2= 0 has two
distinct real roots. Then the equation x2+ 2cx + a2= 0 has(A) two distinct positive real roots (B) two equal roots(C) one positive and one negative root (D) no real roots
eku ysa fd a, b, c okLrfod la[;k,agS rFkk izR;sd lehdj.k x2+ 2ax + b2= 0 ,oa x2+ 2bx + c2= 0 ds nks fofHkUuokLrfod ewy gSA rc lehdj.k x2+ 2cx + a2= 0 ds(A) nks fofHkUu /kukRed okLrfod ewy gksxsaA (B) nks leku ewy gksxsaA(C) ,d /kukRed o ,d _.kkRed ewy gksxkA (D) dksbZ okLrfod ewy ugha gksxkA
Sol. D1= 4a
2
4b
2
> 0 , 4 (a2
b
2
) > 0a2b2> 0 .......... (1)D
2= 4b24c2> 0 , b2c2> 0 ............. (2)
now D = 4c24a2= 4(c2b2+ b2a2)= 4 (b2c2+ a2b2)= 4 (D
1+ D
2)
= Negative
* Equation have no real root.
82. The coefficient of x2012in)x1)(x1(
x12 "!
!is
)x1)(x1(
x12
"!
!esax2012dk ,d xq.kkad gS&
(A) 2010 (B) 2011 (C) 2012 (D) 2013Sol. (1+x) (1+x2)1(1-x)1
(1+x) @M
A
"0r
rr2 )1(x @M
A0r
rx = @M
A
"0r
rr2 )1(x @M
A0r
rx +@M
A
"0r
rr2 )1(x @M
A
!
0r
1r )x(
for Coffi. of x2012= (-1)0+ (-1)1+ (-1)2+ ....... (-1)1006) + ((-1)0 + (-1)1+ ..... +(-1)1005)= 1 + 0= 1No answer
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
28/43
PAGE - 28
KVPY QUESTION PAPER - STREAM (SB / SX)
83. Let (x, y) be a variable point on the curve 4x2+ 9y28x 36y + 15 = 0. Thenmin (x22x + y24y + 5) + max(x22x + y24y + 5) is
;fn o 4x2+ 9y28x 36y + 15 = 0 ij (x, y) ,d pjfcUnq gS] rcmin (x22x + y24y + 5) + max(x22x + y24y + 5) dk eku gksxk&
(A)36
325(B)
325
36(C)
25
13(D)
13
25
Sol. 4x2
+ 9y2
8x
36y + 15 = 04(x2 2x + 1) + 9(y2 4y + 4) 25 = 04(x 1)2+ 9 (y 2)2= 25
2
2
2
2
3
5
)2y(
2
5
)1x(
$%
&'(
)
"!
$%
&'(
)
"= 1
min / 022 )2y()1x( "!" + max. / 0/ 022 )2y(1x "!"
=
2
3
5$%
&'(
)+
2
2
5$%
&'(
)=
36
225100!=
36
325
Ans. (A)
84. The sum of all x 2[0, .] which satisfy the equation sinx +2
1cosx = sin2(x +
4
.) is
;fn x 2[0, .] lehdj.k sinx +2
1cosx = sin2(x +
4
.) dks larq"V djrk gS] rc x ds ,sls lHkh ekuksa dk ;ksx gS&
(A)6
.(B)
6
5.(C) . (D) 2.
Sol. sinx +
2
1cos x = sin2 $
%
&'
(
) .!
4
x
sinx +2
1cosx =
/ 02
2/x2cos1 .!"
sinx +2
1cosx =
2
1
2
1! sin2x
2sinx + cosx = 1 + sin2x2sinx + cosx = 1 + 2 sinx cosx2sinx (1 cosx) 1 (1 cosx) = 0(1 cosx) (2sinx 1) = 0
cos x = 1 or sinx =
2
1
x = 0 x =6
.,
6
5.
sum of roots = 0 +6
.+
6
5.= .
Ans. (C)
85. A polynomila P(x) with real coefficients has the property that P 55(x) -0 for all x. Suppose P(0) = 1 andP5(0) = 1. What can you say about P(1)?cgqin P(x) ds okLrfod xq.kkad bl izdkj gS fd lHkh x ds fy, P55(x) - 0. eku yssa fd P(0) = 1 rFkkP5(0) = 1 rc vki P(1) ds ckjs esa D;k dg ldrs gS ?
(A) P(1) 40 (B) P(1) -0 (C) P(1) #0 (D)2
1< P(1) 1. Then
1n
n
n a
alim
"M6
(A) equals2
1(B) equal 1 (C) equals
5
2(D) does not exists
,d vuqe (an) dks bl izdkj ifjHkkf"kr djssa fd n > 1 ds fy, a
1= 5, an= a
1a
2... a
n1+ 4 rc
1n
n
n a
alim
"M6dk eku
(A)2
1ds cjkcj gSA (B) 1 ds cjkcj gSA (C)
5
2ds cjkcj gSA (D) vfLrRo ugha gSA
Sol. a1
= 5a
n= a
1a
2a
3.......a
n 1+ 4
=n
n1n321
a
aa......aaa+ 4
an=
n
1n
a
4a !+ 4
an2= a
n + 14 + 4a
n
an+1
= an24a
n+ 4 = (a
n2)2
1na ! = an2
n
1n
aa ! = 1
na2 ,
1n
n
aa = 1
1na1
M6nlim n
n 1
a
a "= M6n
limn 1
21
a "
) &' $( %
= 1 ( ! M6nlim a
n= M)
87. The value of the integral dxa1
xcos
x
2
7.
. ! , where a > 0, is
lekdydx
a1
xcos
x
2
7
.
. !,tgk
a > 0dk eku gS&
(A) . (B) a. (C)2
.(D) 2.
Sol. I= 7.
. !
x
2
dxa1
xcos, (a > 0) ...(1)
I= 7.
. !
x
2
dxa1
)x(cos
I= 7.
. !
x
2xdx
a1
xcosa ...(2)
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
30/43
PAGE - 30
KVPY QUESTION PAPER - STREAM (SB / SX)
(1) + (2)
2I= dx)a1(
)a1(xcos
x
x2
7.
. !
!
2I= dxxcos2
0
27.
I=00
1 cos2x 1 sin2xdx x
2 2 2
. .! ) &
A !' $( %7
I= / 0 / 0/ 001 sin2 0 sin02
. ! . ! =2
..
88. Consider
L = 3 2012 + 3 2013 + ... + 3 3011
R = 3 2013 + 3 2014 + ... + 3 3012
and I= dxx33012
2012
7 .
eku ysa fd
L = 3 2012 + 3 2013 + ... + 3 3011
R = 3 2013 + 3 2014 + ... + 3 3012
rFkk I= dxx33012
2012
7 rc
(A) L + R < 2I (B) L + R = 2I (C) L + R > 2I (D)LR
= I
Sol. Since y = x1/3is concave downwards for x > 0
Area of trapezoid AA5B5B < 72013
2012
3/1 dxx
i.e.2
)2013()2012( 3/13/1 !< 7
2013
2012
3/1 dxx
Similarly,2
)2014()2013( 3/13/1 !< 7
2014
2013
3/1 dxx
2
)2015()2014( 3/13/1 !< 7
2015
2014
3/1 dxx
...................................
and so on
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
31/43
PAGE - 31
KVPY QUESTION PAPER - STREAM (SB / SX)
2
)3012()3011( 3/13/1 !< 7
3012
3011
3/1 dxx
Adding we get
2
RL!< 7
3012
2012
3/1 dxx
2
RL!< I
L + R < 2IHence Answer is (A)
89. A man tosses a coin 10 times, scoring 1 point for each head and 2 points for each tail. Let P(K) be the
probability of scoring at least K points. The largest value of K such that P(K) >2
1is
,d vkneh ,d flDds dks 10 ckj mNkyrk gSA mls izR;sd fpk ds fy, 1 vad vkSj izR;sd iV~V ds fy, 2 vad izkIr gksrs
gSA eku ysa fd de ls de K vad izkIr djusdh izkf;drk P(K) gks] rc P(K) >2
1ds fy, K dk vf/kdre eku D;k gksxk?
(A) 14 (B) 15 (C) 16 (D) 17Sol. P(K) = P (at least K points)
x1+ x
2+ x
3+ ....... x
10= K
Coeff xKin (x1+ x2)10
= x10(1 + x)10
coeff xk10in (1 + x)10
= 10CK10
K 410
Now P(K) >2
1
10
10K10
210
110
010
2
C......CCC "!!!!4
2
1
10C0+ 10C
1+ ............. + 10C
K10> 29
1 + 10 + 45 + 120 + 210 + 252 + ...... > 51210C
0+ 10C
1+ 10C
2+ 10C
3+ 10C
4+ 10C
5> 512
K 10 = 5K = 15Ans. (B)
90. Let f(x) =1x
1x
"!
for all x -1. Let f1(x) = f(x), f2(x) = f (f(x)) and generally fn(x) = f(fn1(x)) for n > 1. Let P = f1(2)
f2(3) f3(4) f4(5) which of the following is a multiple of P
eku ysa fd lHkhx -1
ds fy,f(x) =
1x
1x
"
!gSA ;fn
f1(x) = f(x), f2(x) = f (f(x))vkSj
n > 1ds fy, lkekU;r%
fn(x) = f(fn1(x)) gS vkSj P = f1(2) f2(3) f3(4) f4(5). buesa ls P dk xq.kt D;k gksxk?(A) 125 (B) 375 (C) 250 (D) 147
Sol. P = f(2) . f(f(3)) f(f(f(4)) ff(f(f(5)
= $%
&'(
)1
3 $$
%
&''(
)$%
&'(
)2
4f f $$
%
&''(
)$%
&'(
)3
5f
$$
%
&
''
(
)$$%
&''(
)$$%
&''(
)$%
&'(
)4
6fff
= (3) $%
&'(
)1
3 $
$
%
&
''
(
)
$$
%
&
''
(
)
"
!
1
1f
35
35
f $$
%
&
''
(
)
$$
%
&
''
(
)
"
!
1
1f
23
23
= (3) (3) (f(4)) f(f(5))
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
32/43
PAGE - 32
KVPY QUESTION PAPER - STREAM (SB / SX)
= 9 $%
&'(
)3
5 $$
%
&''(
)$%
&'(
)4
6f
= (15)$$$$
%
&
''''
(
)
"
!
12
3
12
3
= (15) (5) = 75375 is multiple of 75.Ans. (B)
PHYSICS
91. The total energy of a black body radiation source is collected for five minutes and used to heat water. The
temperature of the water increases from 10.0C to 11.0C. The absolute temperature of the black body isdoubled and its surface area halved and the experiment repeated for the same time. Which of the following
statements would be most nearly correct?
df".kdk fofdj.k ls mRlftZr dqy tkZ dks5 feuV rd ,df=kr djds ikuh xeZ fd;k tkrk gSA ikuh dk rki 10.0C ls
11.0C gkstkrk gSA df".kdk dk ije rki nq xquk djds ,oa {ks=kQy vk/kk djdsiz;ks x dksmrus gh le; (5 feuV) ds fy,
nksgjk;k trk gSA buesals dkSulk dFku lcls lgh yxrk gS \(A) The temperature of the water would increase from 10.0C to a final temperature of 12C
ikuh dk rki 10.0C ls 12C gks tk;sxkA(B) The temperature of the water would increase from 10.0C to a final temperature of 18C
ikuh dk rki 10.0C ls 18C gks tk,xkA(C) The temperature of the water would increase from 10.0C to a final temperature of 14C
ikuh dk rki 10.0C ls 14C gks tk,xkA(D) The temperature of the water would increase from 10.0C to a final temperature of 11C
ikuh dk rki 10.0C ls 11C gkstk,xkASol. H
1= DAT4 5 = MsGN
1
H2= D
2
A(2T)4 5 = msGq
2
GN2= 8GN
1
GN2= 8C
The temperature of water would increase from 10C to a final temperature of 18C
92. A small asteroid is orbiting around the sun in a circular orbit of radius r0with speed V
0. A rocket is launched
from the asteroid with speed V = 1V0where V is the speed relative to the sun. The highest value of 1forwhich the rocket will remain bound to the solar system is (ignoring gravity due to the asteroid and effect of
other planets)
,d xzfgdk V0osx ls lw;Zds pkjksa vks j r0f=kT;k dso kh; iFk esapDdj yxkrh gS A bl xzfgdk lsV = 1V0osx ls ,d jkdsV
iz{ksfir fd;k tkkrk gS] tgkW V lw;Z ds lkis{k osx gSA 1dk mPpre~ eku D;k gksxk tksjkdsV dks lkSj eaMy ls ca/k j[ksxh \(xzfgdk ,oa vU; xzgksa dsxq:Roh; iz Hkko dks vuns[kk dhft,A)
(A) 2 (B) 2 (C) 3 (D) 1
Sol. Mechanical energy of asteroid
=2
1mv2
0r
GMm
Rocket will remain band to the solar system its B moving energies negative.
0mv2
1
r
GMm 2
0
A!"
2
0
mv2
1
r
GMmA
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
33/43
PAGE - 33
KVPY QUESTION PAPER - STREAM (SB / SX)
20
2
0
vm2
1
r
GMm1A
mv02=
2
1m12v
02
1= 2 .
93. A radioactive nucleus A has a single decay mode with half life OA. Another radioactive nucleus B has twodecay modes 1 and 2. If decay mode 2 were absent, the half life of B would have been OA/2. If decay mode 1
were absent, the half life of B would have been 3 OA. If the actual half life of B is OB, then the ratioA
B
OO
is
,d jsfM;ksa lf; ukfHkd A,dy&{k; iz.kkyh single decay mode) ls {kf;r gksrk gS vkSj bl izf;k dh v/kZ vk;q OAgSA
,d nwljs jsfM;ksa lf; ukfHkd B dh nks{k; iz.kkfy;kW 1 vkSj 2 gSaA ;fn {k; iz.kkyh 2 miyC/k ugha gksrh rks B dh v/kZ vk;q
OA/2 gksrh gSA ;fn {k; iz.kkyh 1 miyC/k ugha gksrh rks B dh v/kZ vk;q 3 OAgksrh gSA ;fn B dh okLrfod v/kZvk;q OBgS rc
vuqikrA
B
O
Odk D;k eku gksxk \
(A)7
3(B)
2
7(C)
3
7(D) 1
Sol. JB= J1+ J2
AAAB 3
2n7
3
2n2n22n
OA
O!
OA
O####
= 7
3
A
B AOO
.
94. A stream of photons having energy 3 eV each impinges on a potassium surface. The work function of
potassium is 2.3 eV. The emerging photo-electrons are slowed down by a copper plate placed 5 mm away.
If the potential difference between the two metal plates is 1V, the maximum distance the electrons can move
away from the potassium surface before being turned back is
3 eV tkZ ds QksVku d.k ,d iksVsf'k;e ds IysV dh lrg ij iM+rs gSaA iksVsf'k;e dk dk;Z Qyu (work function) 2.3
eV gSA mRlftZr QksVksbysDVkWuksadks 5 mm nwj j[ksrkacsds IysV ls/khek fd;k tkrk gS A ;fn nksuksaIys Vksa dschp dk foHkoka rj
1V gks rks] ihNs ykSVusds igys bysDVkWu iksVksf'k;e IysV ls vf/kdre~ fdruh nwjh rd tk ldrs gSa \(A) 3.5 mm (B) 1.5 mm (C) 2.5 mm (D) 5.0 mm
Sol. 3eV
P= 2.3 eVK
max= 3 2.3 = 0.7 eV
5 mm Q1V1V Q5mm0.7 V Q5 0.7 mm = 3.5 mm.
95. Consider three concentric metallic spheres A, B and C of radii a, b, c respectively where a
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
34/43
PAGE - 34
KVPY QUESTION PAPER - STREAM (SB / SX)
Sol. V =c
KQ
b
Kq!
0c
)Qq(kA
!
q + Q = 0q = Q
Vc
KQ)Q(bK A!"
Vb
1
c
1KQ A$
%
&'(
)"
Q = 04)cb(
bcV2.
" .
96. On a bright sunny day a diver of height h stands at the bottom of a lake of depth H. Looking upward, he can
see objects outside the lake in a circular region of radius R. Beyond this circle he sees the images of objects
lying on the floor of the lake. If refractive index of waler is 4/3, then the value of R is :
,d mTtoy fnu esa h yackbZ dk ,d xksrk[ksj H xgjkbZ okys ,d rkykc ds ry ij [kM+k gSA ij dh vksj ns[kus ij og
rkykc ds ckg j dk n'; R f=kT;k ds ok ds nk;jsesa ns[k ldrk gSA bl ok ds ckgj og rkykc ds ry ij fLFkr oLrqvks
ds izfrfcEc gh ns[k ikrk gSA ;fn ty dk viorZukad 4/3 gS rks R dk eku D;k gksxk \
(A)7
)hH(3 "(B) 7h3 (C)
3
7
)hH( "(D)
3
5
)hH( "
Sol.
3
4(sinC) = 1 , sinC =
4
3
tanC =17
3=
hH
R
"
R = )hH(7
3" .
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
35/43
PAGE - 35
KVPY QUESTION PAPER - STREAM (SB / SX)
97. As shown in the figure below, a cube is formed with ten indentical resistance R (thick lines) and two shorting
wires (dotted lines) along the arms AC and BD.
uhpsn'kkZ , fp=k esa ,d ?ku 10 leku ifjek.k okysiz frjks/k Reks Vh js[kk,a rFkk Hkqtkvksa BD ,oa ACdsvuq fn'k nksy|q ifFkr
rkjksa ls cuk gqvk gSA
Resistance between point A and B is
A ,oa B ds chp dk izfrjks/k D;k gksxk \
(A)2
R(B)
6
R5(C)
4
R3(D) R
Sol.
W.S. BridgeRAB= R/2.
98. A standing wave in a pipe with a length L = 1.2 m is described y
,d L = 1.2 ehVj yackbZ ds ikbi eas ,d vizxkkeh rjax dks bl Qyu ls fu:fir fd;k tkrk gSA
y (x, t) = y0 sin :;
?
$%
&'(
) .xL
2
sin :;
? .
!$%
&'(
) .4xL
2
Based on above information, which one of the following statement is incorrect.
(Speed of sound in air is 300 ms1)
ijh nh xbZ tkudkjh ds vk/kkj ij fuEufyf[kr esa ls dkSu lk dFku xyr gS \ /;ku ns fd ok;q esa /ofu dh xfr 300
ms1gSA)(A) A pipe is closed at both ends
ikbi nksuksa fljksa ij can gSA(B) The wavelength of the wave could be 1.2 m
rjax dk rjaxnS/;Z 1.2 m gks ldrk gSA(C) There could be a nods at x = 0 and antinode at x = L/2
x = 0 ij fuLian (node) ,oa x = L/2 ij izLian (antinode) gks ldrk gSA
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
36/43
PAGE - 36
KVPY QUESTION PAPER - STREAM (SB / SX)
(D) The frequency of the fundamental mode of vibrations is 137.5 Hz
daiu dh ewy fo/kk (fundamental mode of vibrations) dh vkofk 137.5 Hz gSASol. From equation
J.2
=L
4., J=
2
L= 0.6 m.
Ans. (B)
99. Two block (1 and 2) of equal mass m are connected by an ideal string (see figure below) over a frictionlesspulley. The blocks are attached to the ground by springs having spring constants k1and k2such that
k1> k2.
fp=k esa ,d vkn'kZ jLlh ls ca/ks leku nzO;eku m ds nks xqVds (1 ,oa 2) ,d ?k"kZ.k jfgr f?kjuh ls yVds gSaA nksuksa xqVdksa
dks nks dekuh (spring) ftudk dekuh fu;rkad k1,oak2gS (k1> k2) ds ek/;e ls tehu ls tksM+ fn;k x;k gSA
Initially, both springs are unstretched. The block 1 is slowly pulled down a distance x and released. Just after
the release the possible value of the magnitudes of the acceleration of the blocks a1and a
2can be
'kq: esa nksuksadekfu;ka esa dksbZf[ka pko rukoughagS A xqVds1 dks /khjs ls uhpsx nwjh rd [khapdj NksM+fn;k tkrk gSA Nks M+us
ds rRdky ckn nksuksa xqVdksa ds Roj.k a1,oa a2dsifjek.k buesa ls dkSu gks ldrs gS \
(A) either $%
&'(
) !AA
m2
x)kk(aa 2121 orvFkok $
%
&'(
)!A"A g
m
xkaandg
m
xka 22
11
(B) $%
&'(
) !AA
m2
x)kk(aa 2121 only dsoy
(C) $%
&
'(
) "
AA m2
x)kk(
aa21
21 only dsoy
(D) either $%
&'(
) "AA
m2
x)kk(aa 2121 orvFkok $$
%
&''(
)"
!AA g
m)kk(
x)kk(aa
21
2121
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
37/43
PAGE - 37
KVPY QUESTION PAPER - STREAM (SB / SX)
Sol.
T + k1x mg = ma
k2x + mg T = ma
T + k1x mg = k
2x + mg T
2T = (k2k
1)x + 2mg
T = mg2
x)kk( 12 !"
a =m2
x)kk( 21!If T is not zero
If T is 0 then
a1=
m
mgxk1 "= g
m
xk1 "
a2=
m
mgxk2 != g
m
xk2 !
100. A simple pendulum is released from rest at the horizontally stretched position. When the string makes an
angle Nwith the vertical, the angle Pwhich the acceleration vector of the bob makes with the string is givenby
,d ljy yksyd dks{kSfrt ls [khaph gqbZ fLFkfr ls fLFkj voLFkk esa NksM+k tkrk gSA tc jLlh /oZ ls Ndks.k cukrh gS] mlle; yksyd ds Roj.k lfn'k ,oa jLlh dh chp dk dks.k PD;k gksxk \
(A) P= 0 (B) P= tan1
$
%
&'(
) N
2
tan
(C) P= tan1
(2 tan N) (D) P= 2
.
Sol.
at= g sinN ........... (i)a
c= v2/# ........... (ii)
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
38/43
PAGE - 38
KVPY QUESTION PAPER - STREAM (SB / SX)
0 + 0 =2
1mv2mg # cosN ........... (iii)
aC= v2/# = 2g cosN
at= g sinN
tanP= at/a
c
= g sinN/2g cosN
=2
tanN
P= $%
&'(
) N"2
tantan 1
Ans. (B)
CHEMISTRY
101. The final major product obtained in the following sequence of reactions is :
fuEufyf[kr vuqfed vfHkf;kvksa dk eq[; vafre mRikn D;k gS \
(A) (B) (C) (D)
Ans. (D)
Sol.
102. In the DNA of E. Coli the mole ratio of adenine to cytosine is 0.7. If the number of moles of adenine in the DNA
is 350000, the number of moles of guanine is equal to :E Coli ds DNAesa ,sMsuhu vkSj lkbVkslhu dk eks yj vuqikr 0.7gSA ;fn DNAesa ,sMsuhu ds eksyksa dh la[;k 350000gSrc Xokuhu ds eksyksa dh la[;k D;k gksxh \(A) 350000 (B) 500000 (C) 225000 (D) 700000
Ans. (B)
Sol.G
3500007.0
C
A
G
TAAA
G =7.0
350000= 5,00,000 Ans.
103. (R)-2-bromobutane upon treatment with aq. NaOH gives(R)-2-czkseksC;qVsu vkSj tyh; NaOH vfHkf;k dk mRikn D;k gksxk \
(A) (B)
(C) (D)
Ans. (C)
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
39/43
PAGE - 39
KVPY QUESTION PAPER - STREAM (SB / SX)
Sol.
104. Phenol on treatment with dil. HNO3gives two products P and Q. P is steam volatile but Q is not. P and Q are
respectivelyQhukWy dk ruq HNO3(dil. HNO
3)ds lkFk foospu djus ij nks mRikn P vkSj Qcurs gSaA PHkki }kjk ok"i'khy (steam
volatile) gS tc fd Q ,slk ugha gSA PvkSj Q e'k% D;k gksaxs \
(A) and (rFkk) (B) and (rFkk)
(C) and (rFkk) (D) and (rFkk)
Ans. (A)
Sol. Phenol on treatment with dil HNO3gives onitrophenol and p-nitrophenol.
onitrophenol has intra molecular Hbonding hence steam volatile ie P, where as Qis p-nitrophenol, Q hasinter molecular H-bonding.
105. A metal is irradiated with light of wavelength 660 nm. Given that the work function of the metal is 1.0 eV, thede-Broglie wavelength of the ejected electron is close to :
,d /kkrq dks 660 nmrjax}S/;Z ds izdk'k ls fdjf.kr (irradiated) fd;k tkrk gSA Kkr gS fd /kkrq dk dk;Z&Qyu (Workfunction)1.0 eVgSA fu"dkflr bysDVku dh Mh&czksXyh (de-Broglie)rjax}S/;Z buesa ls fdl ds fudV gS :(A) 6.6 107m (B) 8.9 1011m (C) 1.3 109m (D) 6.6 1013m
Ans. (C)
Sol. Kinetic energy xfrt tkZ = hRwork function dk;Z Qyu
KE =660
12401
KE = 0.878 eV
J=V
150
J=878.0
150
J= 13.07 = 1.3 109m
106. The inter-planar spacing between the (2 2 1) planes of a cubic lattice of length 450 pm is :
,d ?ku tkyd (Cubic lattice)dh yEckbZ 450 pmgSA blds (2 2 1) ryksa dh varj&ry nwjh D;k gS \(A) 50 pm (B) 150 pm (C) 300 pm (D) 450 pm
Ans. (B)
Sol. 222 Kh
a
#!!= 222 )1()2()2(
450
!!=
3
450= 150 pm
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
40/43
PAGE - 40
KVPY QUESTION PAPER - STREAM (SB / SX)
107. The GH for vaporization of a liquid is 20 kJ/mol. Assuming ideal behaviour, the change in internal energy forthe vaporization of 1 mole of the liquid at 60C and 1 bar is close to :
,d nzo ds ok"iu dh ,UFkSYih] GH dk eku 20 kJ/molgSA ;fn vkn'kZ O;ogkj ekus rks] 60C rkieku vkSj 1 barnkc ijnzo ds 1molds ok"iu ds nkS jku vkarfjd tkZ esagq, ifjorZu dk eku fuEu ds fudV gS :(A) 13.2 kJ/mol (B) 17.2 kJ/mol (C) 19.5 kJ/mol (D) 20.0 kJ/mol
Ans. (B)Sol. GH = 20 kJ/mol
GU = GH GngRT
GU = 20 1031 8.314 (273 + 60)GU = 20 2.768GU = 17.2 kJ/mol
108. Among the following, the species that is both tetrahedral and diamagnetic is :
buesa ls dkSu prq"Qydh; vkSj izfrpqEcdh; nksuksagh gS \(A) [NiCl
4]2 (B) [Ni(CN)
4]2 (C) Ni(CO)
4(D) [Ni(H
2O)
6]2+
Ans. (C)Sol. As in Ni(CO)
4hybridisation of Ni is sp3and CO is strong field effect ligand therefore, it is diamangetic.
Ni(CO)4esa Ni dk ladj.k sp3gS rFkk CO izcy {ks=k fyxs.M gS blfy, ;g izfrpqEcdh; gSA
109. Three moles of an ideal gas expands reversibly under isothermal condition from 2 L to 20 L at 300 K. The
amount of heat-change (in kJ/mol) in the process is :,d vkn'kZxSl dsrhu eks y 300 Kij lerkih voLFkk esa 2 Lls 20 Lrd mRe.kh; rjhds ls iz lkfjr gksrsgSa A bl izf;kesa "ek ifjorZu dk ifjek.k (kJ/molbdkbZ esa ) D;k gS :(A) 0 (B) 7.2 (C) 10.2 (D) 17.2
Ans. (D)
Sol. W = nRT ln1
2
V
V
W = 3R 300 ln 10
=1000
314.8900 9 2.3 = 17.2 kJ/mol.
q = W = 17.2 kJ/mol. (For isothermal process lerkih; ize ds fy, GE = 0).
110. The following data are obtained for a reaction, X + Y 6Products.Expt. [X
0]/mol [Y
0]/mol rate/mol L1s1
1 0.25 0.25 1.0 106
2 0.50 0.25 4.0 106
3 0.25 0.50 8.0 106
The overall order of the reaction is :(A) 2 (B) 4 (C) 3 (D) 5
vfHkf;k X + Y 6mRIkkn ds fy, fuEufyf[kr vkadM+s izkIr gq,Aiz;ksx vuqe [X
0]/eksy [Y
0]/eksy nj/eksy L1s1
1 0.25 0.25 1.0 106
2 0.50 0.25 4.0 106
3 0.25 0.50 8.0 106
bl vfHkf;k dh lexz dksfV (overall order of the reaction) D;k gS \(A) 2 (B) 4 (C) 3 (D) 5
Ans. (D)
Sol. Rate nj = K . [X]p[Y]q
From expt. 1 and 2, p = 2 and from expt. 1 and 3, q = 3. Therefore, over all order = 5.
iz;ksx 1 o 2 ls p = 2 rFkk iz;ksx 1 o 3 ls q = 3Ablfy, lEiw.kZ dksfV = 5 gSA
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
41/43
PAGE - 41
KVPY QUESTION PAPER - STREAM (SB / SX)
BIOLOGY111. When hydrogen peroxide is applied on the wound as a disinfectant, there is frothing at the site of injury,
which is due to the presence of an enzyme in th skin that uses hydrogen peroxide as a substrate to produce(A) hydrogen (B) carbon dioxide (C) water (D) oxygen
Ans (D)
tc gkbMkstu ijvkDlkbM ?kko ij jksxk.kq & uk'kd ds rkSj ij yxk;k tkrk gS] rc >kx curk gSA bldh otg Ropk esamifLFkr fd.od (enzyme)gS tks gkbMkstu ijvkDlkbM ls fuEufyf[kr dks eqDr djrk gSS &
(A) gkbZMkstu (B) ikuh (C) dkCkZuMkbZvkDlkbM (D)vkDlhtu
112. Persons suffering from hypertension (high blood pressure) are advised a low-salt diet because(A) more salt is absorbed in the body of a patient with hypertension(B) high salt leads to water retention in the blood that further increases the blood pressure(C) high salt increases nerve conduction and increases blood pressure(D) high salt causes adrenaline release that increases blood pressure
Ans (B)
mPp jDrpki ls ihfMr O;fDr dksued de ysus dh lykg nh tkrh gSA D;ksafd]
(A) mPp jDrpki ds dkj.k ued dk vo'kks"k.k T;knk gksrk gS
(B) T;knk ued ds dkj.k [kqu esa ikuh dk izfr/kkj.k gksrk gS ftlds dkj.k jDrpki c
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
42/43
PAGE - 42
KVPY QUESTION PAPER - STREAM (SB / SX)
116. Which one of the following is true about enzyme catalysis ?(A) the enzyme changes at the end of the reaction(B) the activation barrier of the process is lower in the presence of an enzyme(C) the rate of the reaction is retarded in the presence of an enzyme(D) the rate of the reaction is independent of substrate concentration
Ans (B)
fd.od (enzyme)mRizsj.k (catalysis)ds ckjs esa dkSu lk fuEufyf[kr dFku lgh gS\
(A) vfHkf;k dsckn fd.od esa cnyko vkrk gSS A
(B) fd.od ds tfj;s lf;.k jks/k (activation barrier)de gks tkrk gS
(C) fd.od ds tfj, vfHkf;k dh xfr de gks tkrh gSA
(D)vfHkf;k dh xfr dk;ZnzO; (substrate)lkaUnzrk ij fuHkZj ugha djrhAAns (B)
117. Vibrio cholerae causes cholera in humans. Ganga water was once used successfully to combat the infec-tion. The possible reason could be -(A) high salt content of Ganga water(B) low salt content of Ganga water(C) presence of bacteriophages in Ganga water(D) presence of antibiotics in Ganga water
Ans (C)euq";ksa esa dkWysjk jksx fofcz;ksa dkWysjs dhVk.kqls gksrk gS A xaxkty dslsou ls bl lae.k dksjksdk tk ldrk FkkA bldk D;kdkj.k gk ldrk gS\
(A) xaxkty esa ued dh ek=kk vf/kd gSA (B) xaxkty esa ued dh ek=kk de gS
(C) xaxkty esathok.kqHkksth (bacteriophages)gS A (D)xaxkty esa izfrtSfodh (antibiotics )gSaAAns (C)
118. When a person begins to fast, after some time glycogen stored in the liver is mobilized as a source ofglucose. Which of the following graphs best represents the change of glucose level (y-axis) in his blood,starting from the time (x-axis) when he begins to fast ?
(A) (B)
(C) (D)
Ans (C)
-
8/13/2019 Kvpy 2012 Sb Sx Solution1
43/43
KVPY QUESTION PAPER - STREAM (SB / SX)
miokl 'kq: djusds dqN le; (time x v{k ds ckn ;dr ds Xykbdkstu ds HkaMkj dk Xywdkst (glucose y v{k
esa ifjorZu 'kq: gksrk gSA fuEufyf[kr fdl xzkQ esa miokl djus okys ds jDr esa Xywdkst dh ek=kk dks lgh n'kkZ;k
x;k gS\
(A) (B)
(C) (D)
Ans (C)
119. The following sequence contains the open reading frame of a polypeptide. How many amino acids will thepolypeptide consist of ?5AGCATATGATCGTTTCTCTGCTTTGAACT3(A) 4 (B) 2 (C) 10 (D) 7
Ans (D)
fuEufyf[krcc DNA ds vuqe esa ,d isiVkbM dk vksiu jhfMax se gSA ;g isiVkbM fdrus vehuksa ,flM dk gksxk\ 5'AGCATATGATCGTTTCTCTOGCTTTGAACT - 3'(A) 4 (B) 2 (C) 10 (D) 7
Ans (D)
120. Insects constitute the largest animal group on earth. About 25-30% of the insect species are known to beherbivores. In spite of such huge herbiore perssure, globally, green plants have persisted. One possiblereason for this persistence is :(A) food preference of insects has tended to change with time(B) herbivore insects have become inefficient feeders of green plants(C) herbivore population has been kept in control by predators(D) decline in reproduction of herbivores with time
Ans (C)
iFoh ds izk.kh lewg esa dhVk sa dh ek=kk lcls T;knk gSA 25% - 30% dhVd tkfr 'kkdkgkjh gSA fQj Hkh ouLifr dh ek=kk esacnyko ugha vk;k gSA bldk dkj.k D;k gks ldrk gS\(A) dhVksa dh [kk| izkf;drk le; ds lkFk ifjofrZr gksrh jgrh gSA(B) 'kkdkgkjh dhV gjs ikniksa ds vi;kZIr Hk{kd gksrs gSaA(C) 'kkdkgkjh;kjsa dsleqnk; dks ijHkf{k;ksa }kjk fu;af=kr j[kk tkrk gSA(D) 'kkdkgkjh dhVksa ds iztuu esa le; dslkFk deh gksrh tkrh gSA
Ans (C)