Bansal classesjee main2013_answer_key_bansal classes jee main 2013 answer key

Author
bansalclassespvtltd 
Category
Documents

view
529 
download
1
Embed Size (px)
Transcript of Bansal classesjee main2013_answer_key_bansal classes jee main 2013 answer key
JEE Main 2013  Answer Key Code QQuestion QuestionQuestionQuestionQuestionQuestionAnswer AnswerAnswerAnswerAnswerAnswer
Helpline No: 08003045222, 08003046222, 08003018222, 07442423738/ 39www.bansal.ac.in
JEE (Advanced) Crash CourseStarting from 10th April 2013
JEE Advanced 2013JEE Advanced 2013
JEE Advanced 2014 JEE Main 2014
Final Step PackageFinal Step Package(Available in Online & Offline Mode)
Crash Course Starting from 10 April, 2013th
*50% Cash back reward*Conditions Apply
Sterling Starting from 29 April, 2013 (PhaseI)th
PhaseII  20th May  PhaseIII  17th June  PhaseIV  8th July
Legend Starting from 13 May, 2013 (PhaseI)th
PhaseII  10th June  PhaseIII  1th July  PhaseIV 15th July
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
1
1
1
4
4
3
2
1
3
1 & 4
2 & 4
1
1
3
2
4
4
2
4
3
3
2
2
4
2
1
3
4
3
2
2
4
1
1
3
4
2
4
1
4
2
1
4
1
3
3
1
2
3
1
1
4
2
2
2
2
2
4
2
2
2
1
3
2
4
2
3
3
3
3
3
2
1
1
1
3
4
1
1
2
2
3
4
2
4
3
2
2
1
1
Q.1 An unknownalcohol is treated with the "Lucasreagent" to determine whether the alcohol isprimary, secondaryor tertiary. Which alcoholreacts fastest and bywhat mechanism:(1) tertiary alcohol by SN1(2) secondary alcohol by SN2(3) tertiary alcohol by SN2(4) secondary alcohol by SN1
Ans. 1
Q.2 The first ionisation potential of Na is 5.1 eV.The value of electrongain enthalpyof Na+ willbe:(1) –5.1 eV (2) –10.2 eV(3) +2.55 eV (4) –2.55 eV
Ans. 1
Q.3 Stability of the species Li2, Li2¯ and Li2+
increases in the order of:(1) Li2¯ < Li2
+ < Li2
(2) Li2 < Li2¯ < Li2+
(3) Li2¯ < Li2 < Li2+
(4) Li2 < Li2+ < Li2¯
Ans. 1
Q.4 The molarityof a solution obtained bymixing750 mLof 0.5 (M) HCl with 250 mL of 2 (M)HClwillbe:(1) 1.00 M (2) 1.75 M(3) 0.975 M (4) 0.875 M
Ans. 4
Q.5 Whichofthe followingis thewrongstatement?(1) O3 molecule is bent(2) Ozone is violetblack in solid state(3) Ozone is diamagnetic gas(4) ONCl and ONO¯ are not isoelectronic.
Ans. 4
Q.6 Four successive members of the first rowtransitionelementsarelistedbelowwithatomicnumbers. Which one of them is expected to
have the highest 0
M/M 23E value?
(1) Mn (Z = 25) (2) Fe (Z = 26)(3) Co (Z = 27) (4) Cr (Z = 24)
Ans. 3
Q.7 A solution of (–) – 1–chloro –1– phenylethaneon toluene racemises slowlyin the presence ofa small amount of SbCl5 due to the formationof::(1) carbene (2) carbocation(3) free radical (4) carbanion
Ans. 2
Q.8 The coagulating power of electrolytes havingions Na+,Al3+ and Ba2+ for arsenic sulphidesol increases in the order :(1) Na+ < Ba2+ < Al3+
(2) Ba2+ < Na+ < Al3+
(3) Al3+ < Na+ < Ba2+
(4) Al3+ < Ba2+ < Na+
Ans. 1
Q.9 How many litres of water must be added to 1litre of an aqueous solution of HCl with a pHof 1 to create an aqueous solution with pH of2?(1) 0.9 L (2) 2.0 L(3) 9.0 L (4) 0.1 L
Ans. 3
Q.10 Which one of the following molecules isexpected to exhibit diamagnetic behaviour?(1) N2 (2) O2(3) S2 (4) C2
Ans. 1 and 4
Q.11 Which of the following arrangements does notrepresent the correct order of the propertystated against it?(1) Ni2+ < Co2+ < Fe2+ < Mn2+ : ionic size(2) Co3+ < Fe3+ < Cr3+ < Sc3+ : stability inaqueous solution(3) Sc < Ti < Cr < Mn : number of oxidationstates(4) V2+ < Cr2+ < Mn2+ < Fe2+ : paramagneticbehaviour
Ans. 2 and 4
Q.12 Experimentallyit was found that ametal oxidehas formula M0.98O. Metal M, is present asM2+ and M3+ in its oxide. Fraction of the metalwhich exists as M3+ would be :(1) 4.08 % (2) 6.05 %(3) 5.08 % (4) 7.01 %
Ans. 1
Q.13 A compound with molecular mass 180 isacylated with CH3COCl to get a compoundwithmolecularmass390.Thenumberofaminogroups present per molecule of the formercompound is:(1) 5 (2) 4(3) 6 (4) 2
Ans. 1
Q.14 Given
V74.0E0
Cr/Cr3 ; V51.1E0
Mn/MnO 24
V33.1E0
Cr/OCr 3272
; V36.1E0¯Cl/Cl
Based on the data given above, strongestoxidisingagentwillbe:(1) Cr3+ (2) Mn2+
(3) MnO4¯ (4) Cl¯Ans. 3
Q.15 Arrange the following compounds in order ofdecreasing acidity :
OH OH OH OH
Cl CH3 NO2 OCH3
(I) (II) (III) (IV)
(1) I > II > III > IV(2) III > I > II > IV(3) IV > III > I > II(4) II > IV > I > III
Ans. 2
Q.16 The rate of a reaction doubles when itstemperature changes from 300 K to 310 K.Activation energyof such a reaction will be:(R = 8.314 JK–1 mol–1 and log 2 = 0.301)(1) 48.6 kJ mol–1
(2) 58.5 kJ mol–1
(3) 60.5 kJ mol–1
(4) 53.6 kJ mol–1
Ans. 4
Q.17 Synthesis of each molecule of glucose inphotosynthesis involves:(1) 10 molecules ofATP(2) 8 molecules ofATP(3) 6 molecules ofATP(4) 18 molecules ofATP
Ans. 4
Q.18 Which of the following complex species is notexpected to exhibit optical isomerism?(1) [Co(en)2Cl2]
+
(2) [Co(NH3)3Cl3](3) [Co(en)(NH3)2Cl2]
+
(4) [Co(en)3]3+
Ans. 2
Q.19 A piston filled with 0.04 mol of an ideal gasexpands reversibly from 50.0 mL to 375 mLat a constant temperature of 37.0°C.As it doesso, it absorbs 208 J of heat. The values of qand w for the process will be:(R = 8.314 J / mol K) (ln 7.5 = 2.01)(1) q = –208 J, w = –208 J(2) q = –208 J, w = +208 J(3) q = +208 J, w = +208 J(4) q = +208 J, w = –208 J
Ans. 4
Q.20 Agaseoushydrocarbongivesuponcombustion0.72 g of water and 3.08 g of CO2. Theempirical formula of the hydrocarbon is:(1) C3H4 (2) C6H4(3) C7H8 (4) C2H4
Ans. 3
Q.21 The order of stability of the followingcarbocations:
CH = CH – CH ; CH CH – CH2 2 3 2 2– ;
(II) (III)(I)
CH2
is(1) II > III > I (2) I > II > III(3) III > I > II (4) III > II > I
Ans. 3
Q.22 Which of the following represents the correctorder of increasingfirst ionization enthalpyforCa, Ba, S, Se and Ar?(1) S < Se < Ca < Ba < Ar(2) Ba < Ca < Se < S < Ar(3) Ca < Ba < S < Se < Ar(4) Ca < S < Ba < Se < Ar
Ans. 2
Q.23 For gaseous state, if most probable speed is
denoted by C*, average speed by C and
mean square speed by C, then for a largenumber of molecules the ratios of these speedsare:
(1) C* : C : C = 1.128 : 1.225 : 1
(2) C* : C : C = 1 : 1.128 : 1.225
(3) C* : C : C = 1 : 1.225 : 1.128
(4) C* : C : C = 1.225 : 1.128 : 1Ans. 2
Q.24 The gas leaked from a storage tank of theUnionCarbideplant inBhopalgastragedywas:(1) Methylamine(2)Ammonia(3) Phosgene(4) Methylisocyanate
Ans. 4
Q.25 Consider the following reaction:xMNO4¯ + yC2O4
2– + zH+
xMn2+ + 2yCO2 +2
zH2O
The value of x, y and z in the reaction are,respectively:(1) 2, 5 and 8 (2) 2, 5 and 16(3) 5, 2 and 8 (4) 5, 2 and 16
Ans. 2
Q.26 Whichofthefollowingexistsascovalentcrystalin the solid state?(1) Silicon (2) Sulphur(3) Phosphorus (4) Iodine
Ans. 1
Q.27 Compound (A), C8H9Br, gives a whiteprecipitate when warmed with alcoholicAgNO3. Oxidation of (A) gives an acid (B),C8H6O4. (B)easilyformsanhydrideonheating.Identify the compound (A).
(1)
C H2 5
Br
(2)
CH2Br
CH3
(3)
CH2Br
CH3
(4)
CH2Br
CH3
Ans. 3
Q.28 Energy of an electron is given by
E = –2.178 × 10–18 J
2
2
n
Z. Wavelength of
light required to excite an electron in anhydrogen atom from level n = 1 to n = 2 willbe:(h = 6.62 × 10–34 Js and c = 3.0 × 108 ms–1)(1) 2.816 × 10–7 m(2) 6.500 × 10–7 m(3) 8.500 × 10–7 m(4) 1.214 × 10–7 m
Ans. 4
Q.29 An organic compoundA upon reacting withNH3 gives B. On heating B give C, C inpresence of KOH reacts with Br2 to giveCH3CH2NH2. A is(1) CH3CH2CH2COOH
(2)
CH3
CH3–CH–COOH
(3) CH3CH2COOH(4) CH3COOH
Ans. 3
Q.30 In which of the following pairs of molecules /ions, both the species are not likely to exist?(1) H2¯, He2
2– (2) H22+, He2
(3) H2¯, He22+ (4) H2
+, He22–
Ans. 2
Q.31 Thecirclepassingthrough(1,–2)and touchingthe axis of x at (3, 0) also passes through thepoint(1) (2, – 5)(2) (5, – 2)(3) (– 2, 5)(4) (– 5, 2)
Ans. [2]
Q.32 ABCD is a trapezium such that AB and CDare parallel and BC CD. If ADB = ,BC = p and CD = q, then AB is equal to
(1)
sinqcosp
cosqp 22
(2)
sinqcosp
qp22
22
(3) 2
22
)sinqcosp(
sin)qp(
(4)
sinqcosp
sin)qp( 22
Ans. [4]
Q.33 Given :Acircle 2x2 + 2y2 = 5 and a parabola
y2 = 4 5 x.
StatementI: An equation of a common
tangent to these curves is y = x + 5 .
StatementII: If the line y = mx +m
5
(m0)is theircommontangent, thenmsatisfiesm4 – 3m2 + 2 = 0.(1) StatementI is true, StatementII is true,StatementII is not a correct explanation forStatementI.(2) StatementI is true, StatementII is false.(3) StatementI is false, StatementII is true.(4) StatementI is true, StatementII is true,StatementII is a correct explanation forStatementI.
Ans. [1]
Q.34 A ray of light along x + 3 y = 3 gets
reflected upon reachingxaxis, the equation ofthe reflected ray is
(1) 3 y = x – 3
(2) y = 3 x – 3
(3) 3 y = x – 1
(4) y = x + 3
Ans. [1]
Q.35 All the students of a class performed poorly inMathematics. The teacher decided to givegrace marks of 10 to each of the students.Whichof thefollowingstatisticalmeasureswillnot change even after the grace were given?(1) median (2) mode(3) variance (4) mean
Ans. [3]
Q.36 If x, y, z are in A.P. and tan–1x, tan–1y andtan–1z are also inA.P., then(1) 2x = 3y = 6z(2) 6x = 3y = 2z(3) 6x = 4y = 3z(4) x = y = z
Ans. [4]
Q.37 If dx)x(f = (x), then dx)x(fx 35 is
equal to
(1)3
1x3(x3) – 3 dx)x(x 33 + C
(2)3
1x3(x3) – dx)x(x 32 + C
(3) dx)x(x)x(x3
1 3333 + C
(4) dx)x(x)x(x3
1 3233 + C
Ans. [2]Q.38 The equation of the circle passing through the
foci of the ellipse9
y
16
x 22
= 1 and having
centre at (0, 3) is(1) x2 + y2 – 6y + 7 = 0(2) x2 + y2 – 6y – 5 = 0(3) x2 + y2 – 6y + 5 = 0(4) x2 + y2 – 6y – 7 = 0
Ans. [4]
Q.39 The xcoordinateof the incentre of the trianglethat has the coordinates of mid points of itssides as (0, 1), (1, 1) and (1, 0) is
(1) 2 – 2 (2) 1 + 2
(3) 1 – 2 (4) 2 + 2Ans. [1]
Q.40 The intercepts on xaxis made by tangents to
thecurve,y= x
0
dtt ,xR,whichareparallel
to the line y = 2x are equal to(1) ± 2 (2) ± 3(3) ± 4 (4) ± 1
Ans. [4]
Q.41 The sum of first 20 terms of the sequence0.7, 0.77, 0.777, .........., is
(1)9
7(99 – 10–20)
(2)81
7(179 + 10–20)
(3)9
7(99 +10–20)
(4)81
7(179 – 10–20)
Ans. [2]
Q.42 ConsiderStatement1: (p ~ q) (~ p q) is afallacy.Statement2: (p q) (~ q ~ p) is atautology.(1) StatementI is true, StatementII is true,StatementII is not a correct explanation forStatementI.(2) StatementI is true, StatementII is false.(3) StatementI is false, StatementII is true.(4) StatementI is true, StatementII is true,StatementII is a correct explanation forStatementI.
Ans. [1]
Q.43 The area (in square units) bounded by the
curves y = x , 2y – x + 3 = 0, xaxis andlying in the first quadrant is(1) 36 (2) 18
(3)4
27(4) 9
Ans. [4]
Q.44 The expressionAtan1
Acot
Acot1
Atan
can be
written as(1) sec A cosec A + 1(2) tan A + cot A(3) sec A + cosec A(4) sin A cos A + 1
Ans. [1]
Q.45 The real number k for which the equation2x3 + 3x + k = 0 has two distinct real roots in[0, 1](1) lies between 2 and 3.(2) lies between – 1 and 0.(3) does not exist.(4) lies between 1 and 2.
Ans. [3]
Q.46x4tanx
)xcos3()x2cos1(Lim
0x
is equal to
(1)2
1(2) 1
(3) 2 (4)4
1
Ans. [3]
Q.47 Let Tn be the number of all possible trianglesformedbyjoiningvertices ofannsided regularpolygon. If Tn+1 – Tn = 10, then the value of nis(1) 5 (2) 10(3) 8 (4) 7
Ans. [1]
Q.48 Atpresent, a firmismanufacturing2000 items.It is estimated that the rate of change ofproduction P w.r.t. additional number of
workers x is given bydx
dP= 100 – 12 x .
If the firm employs 25 more workers, then thenew level of production of items is(1) 3000 (2) 3500(3) 4500 (4) 2500
Ans. [2]
Q.49 Statement1: The value of the integral
3
6xtan1
dxis equal to
6
.
Statement2: b
a
dx)x(f = b
a
dx)xba(f .
(1) StatementI is true, StatementII is true,StatementII is not a correct explanation forStatementI.(2) StatementI is true, StatementII is false.(3) StatementI is false, StatementII is true.(4) StatementI is true, StatementII is true,StatementII is a correct explanation forStatementI.
Ans. [3]
Q.50 If P =
44233131
is the adjoint of a 3 × 3
matrix A and A  = 4, then is equal to(1) 11 (2) 5(3) 0 (4) 4
Ans. [1]
Q.51 Thenumberofvaluesofk, forwhichthesystemofequations:(k + 1) x + 8y = 4kkx + (k + 3) y = 3k – 1has no solution is(1) 1 (2) 2(3) 3 (4)infinite
Ans. [1]
Q.52 If y= sec (tan–1x), thendx
dyat x = 1 is equal to
(1)2
1(2) 1
(3) 2 (4)2
1
Ans. [4]
Q.53 If the lines1
2x =
1
3y =
k
4z
and
k
1x =
2
4y =
1
5z are coplanar, then k
can have(1) exactlyone value(2) exactly two values(3) exactly three values(4) any value
Ans. [2]
Q.54 LetAand B be two sets containing 2 elementsand 4 elements respectively. The number ofsubsets ofA× B having 3 or more elements is(1) 220 (2) 219(3) 211 (4) 256
Ans. [2]
Q.55 If the vectors k4i3AB and
k4j2i5AC are the sides of a triangle
ABC, then the length of the median throughAis
(1) 72 (2) 33
(3) 45 (4) 18
Ans. [2]
Q.56 Amultiplechoiceexaminationhas5questions.Each question has three alternative answers ofwhich exactly one is correct. The probabilitythat astudentwill get4ormorecorrect answersjust byguessing is
(1) 53
13(2) 53
11
(3) 53
10(4) 53
17
Ans. [2]
Q.57 If z is a complex number of unit modulus and
argument , then arg
z1
z1equals
(1)
2(2)
(3) – (4) – Ans. [2]
Q.58 If the equation x2 + 2x + 3 = 0 andax2 + bx + c = 0, a, b, cR, have a commonroot, then a : b : c is(1) 3 : 2 : 1 (2) 1 : 3 : 2(3) 3 : 1 : 2 (4) 1 : 2 : 3
Ans. [4]
Q.59 Distance between two parallel planes2x + y + 2z = 8 and 4x + 2y + 4z + 5 = 0 is
(1)2
5(2)
2
7
(3)2
9(4)
2
3
Ans. [2]
Q.60 The term independent of x in expansion of
10
2
1
3
1
3
2
xx
1x
1xx
1x
is
(1) 120 (2) 210(3) 310 (4) 4
Ans. [2]
Q.61 In an LCR circuit as shown below bothswitches are open initially. Now switch S1 isclosed, S2 kept open. (q is charge on thecapacitor and = RC is Capacitive timeconstant). Which of the following statement iscorrect ?
V
R
C
L
S1
S2
(1) At t = , q = CV/2(2) At t = 2, q = CV(1– e–2)
(3) At t =2
, q = CV(1– e–1)
(4) Work done by the battery is half of theenergy dissipated in the resistor
Ans. [2]
Q.62 A diodedetector is used to detect an amplitudemodulated wave of 60% modulation byusinga condenser of capacity 250 pico farad inparallel with a load resistance 100 kilo ohm.Findthemaximummodulatedfrequencywhichcould be detected by it.(1) 10.62 kHz (2) 5.31 MHz(3) 5.31 kHz (4) 10.62 MHz
Ans. [1]
Q.63 The supply voltage to a room is 120 V. Theresistance of the lead wires is 6.A60W bulbis already switched on. What is the decreaseof voltage across the bulb, when a 240 Wheater is switched on in parallel to the bulb ?(1) 2.9 Volt (2) 13.3 Volt(3) 10.04 Volt (4) zero Volt
Ans. [3]
Q.64 A uniform cylinder of length L and mass Mhaving crosssectional area A is suspended,with its length vertical, from a fixed point byamassless spring, such that it is half submergedin a liquid of densityat equilibrium position.The extension x0 of the spring when it is inequilibriumis:
(1)
M
LA1
k
Mg(2)
M2
LA1
k
Mg
(3)
M
LA1
k
Mg(4)
k
Mg
(Here k is spring constant)Ans. [2]
Q.65 Two charges, each equal to q, are kept at x =–a and x = a on the xaxis.Aparticle of mass
m and charge q0 =2
qis placed at the origin. If
charge q0 is given a small displacement (y <<a) along the yaxis, the net force acting on theparticle is proportional to :
(1) –y (2)y
1
(3) –y
1(4) y
Ans. [4]
Q.66 A beam of unpolarised light of intensity I0 ispassed through a polaroidAand then throughanother polaroid Bwhich is oriented so that itspricipal plane makes an angle of 45° relativeto that ofA.The intensityof the emergent lightis:(1) I0/2 (2) I0/4(3) I0/8 (4) I0
Ans. [2]
Q.67 The anode voltage of a photocell is kept fixed.The wavelength of the light falling on thecathode isgraduallychanged.Theplate currentI of the photocell varies as follows :
(1)
I
O
(2)
I
O
(3)
O
I
(4)
I
O
Ans. [3]
Q.68 Two coherent point sources S1 and S2 areseparated bya small distance 'd' as shown. Thefringes obtained on the screen will be :
D
S1 S2
d
Screen
(1) straight lines (2) semicircles(3) concentric circles (4) points
Ans. [3]
Q.69 A metallic rod of length l is tied to a string oflength21andmade to rotatewithangular speedonahorzontal tablewithoneendof thestringfixed. If there is a vertical magnetic field 'B' inthe region, the e.m.f. induced across the endof the rod is
(1)2
B3 2l(2)
2
B4 2l
(3)2
B5 2l(4)
2
B2 2l
Ans. [3]
Q.70 In a hydrogen like atom electron makestransition from an energy level with quantumnumber n to another with quantum number(n – 1). If n >>1, the frequency of radiationemitted is proportional to
(1) 2n
1(2) 23n
1
(3) 3n
1(4)
n
1
Ans. [3]
Q.71 Assume that a drop of liquid evaporates bydecrease in its surface energy, so that itstemperature remains unchanged. What shouldbe the minimum radius of the drop for this tobe possible? The surface tension is T, densityof liquid is and L is its latent heat ofvaporization.
(1) LT (2) LT
(3) LT2 (4) TL
Ans. [3]
Q.72 The graph between angle of deviation () andangle of incidence (i) for a triangular prism isrepresented by :
(1)
O i
(2)
O i
(3)
O i
(4)
O i
Ans. [2]
Q.73 Let [0] denote thedimensional formula of thepermittivityofvacuum.IfM=mass,L=length,T = time andA= electric current, then(1) [0] = [M–1L–3T4A2](2) [0] = [M–1L2T–1A–2](3) [0] = [M–1L2T–1A](4) [0] = [M–1L–3T2A]
Ans. [1]
Q.74
v0
v2v0
p p0
2p0
The above pv diagram represents thethermodynamic cycle of an engine, operatingwith an ideal monoatomic gas. The amount ofheat, extractedfromthesource inasinglecycle,is
(1) 00vp2
13
(2) 00vp
2
11
(3) 00vp4 (4) 00vp
Ans. [1]
Q.75 A sonometer wire of length 1.5 m is made ofsteel. Thetension in itproducesanelastic strainof 1%. What is the fundamental frequency ofsteel ifdensityandelasticityofsteelare7.7×103
kg/m3 and 2.2 × 1011 N/m2 respectively?(1) 178.2 Hz (2) 200.5 Hz(3) 770 Hz (4) 188.5 Hz
Ans. [1]
Q.76 This question has statement Iand statement II.Of the four choices given after the statements,choose the one that best describes the twostatements.StatementI: Higher the range, greater is theresistance of ammeter.StatementII: To increase the range ofammeter, additional shunt needs to be usedacross it.(1) StatementI is true, StatementII is true,StatementII is not the correct explanation ofStatementI.(2) StatementI is true, StatementII is false.(3) StatementI is false, StatementII is true.(4) StatementI is true, StatementII is true,StatementII is the correct explanation ofStatementI.
Ans. [3]
Q.77 What is theminimumenergyrequiredto launchasatelliteofmassmfromthesurfaceofaplanetof mass M and radius R in a circular orbit at analtitude of 2R?
(1)R3
GmM2(2)
R2
GmM
(3)R3
GmM(4)
R6
GmM5
Ans. [4]
Q.78 A projectile is given an initial velocity of
j2i m/s, where i is along the ground and
j is along the vertical. If g = 10 m/s2, the
equation of its trajectory is(1) y = 2x – 5x2 (2) 4y = 2x – 5x2
(3) 4y = 2x – 25x2 (4) y = x – 5x2
Ans. [1]
Q.79 Two capacitors C1 and C2 are charged to120V and 200V respectively. It is found thatby connecting them together the potential oneach one can be made zero. Then(1) 3C1 = 5C2 (2) 3C1 + 5C2 = 0(3) 9C1 = 4C2 (4) 5C1 = 3C2
Ans. [1]
Q.80 A hoop of radius r and mass mrotating with anangular velocity 0 is placed on a roughhorizontal surface. The initial velocity of thecentre of the hoop is zero. What will be thevelocityof thecentreof thehoopwhen it ceasesto slip?
(1)3
r 0(2)
2
r 0
(3) 0r (4)4
r 0
Ans. [2]
Q.81 An ideal gas enclosed in a vertical cylindricalcontainer supposrs a freely moving piston ofmass M. The poston and the cylinder haveequal cross sectional areaA. When the pistonis in equilibrium, the volume of the gas is V0and its pressure is P0. The piston is slightlydisplaced from the equilibrium position andreleased. Assuming that the system iscompletely isolated from its surrounding, thepiston executes a sime harmonic motion withfrequency.
(1) 2
00
A
MPV
2
1(2)
0
02
MV
PA
2
1
(3)0
0
PA
MV
2
1
(4) MV
PA
2
1
0
0
Ans. [2]
Q.82 A chargeQ is uniformlydistributedovera longrodAB of length Las shown in the figure.Theelectric potential at the point O lying at adistance Lfrom the endAis
A B
LLO
(1) L4
Q3
0 (2) 2nL4
Q
0 l
(3) L4
2nQ
0
l(4) L8
Q
0
Ans. [3]
Q.83 A circular loop of radius 0.3 cm lies parallel toa much bigger circular loop of radius 20 cm.The centre of the small loop is on the axis ofthebigger loop. The distance between their centreis 15 cm. If a current of 2.0 A flows throughthesmaller loop, thenthefluxlinkedwithbiggerloop is :(1) 6 × 10–11 weber(2) 3.3 × 10–11 weber(3) 6.6 × 10–9 weber(4) 9.1 × 10–11 weber
Ans. [4]
Q.84 If a piece of metal is heated to temperature and then allowed to cool in a room which is attemperature 0, the graph between thetemperature T of the metal and time t will beclosest to
(1)
t
T
0
O
(2)
T
0
O t
(3) 0
O
T
t
(4)
T
O t
Ans. [2]
Q.85 The IV characteristic of an LED is
(1)
I
O V
RYGB
(2)
O V
I
(3)
V O
I
R
Y
GB
(4)I
O V
(R)(Y)(G) (B)
Red
Yel
low
Gre
enB
lue
Ans. [4]
Q.86 This question hasstatementIand statementII.Of the four choices given after the statements,choose the one that best describes the twostatements.StatementI: A point particle of mass mmoving with speed v collides with stationarypoint particle of mass M. If the maximum
energy loss possible is given as
2mv2
1f
then f =
mM
m.
StatementII: Maximum energy loss occurswhen theparticles get stuck together as a resultof the collision..(1) StatementI is true, StatementII is true,StatementII is not a correct explanation ofStatementI(2) StatementI is true, StatementII is false(3) StatementI is false, StatementII is true(4) StatementI is true, StatementII is true,StatementII is a correct explanation ofStatementI.
Ans. [3]
Q.87 Theamplitudeofadampedoscillatordecreasesto 0.9 times its original magnitude in 5s. Inanother 10 s it will decrease to times itsoriginal magnitude, whereequals :(1) 0.81 (2) 0.729(3) 0.6 (4) 0.7
Ans. [2]
Q.88 Diameter of a plano  convex lens is 6 cm andthickness at the centre is 3 mm. If speed oflight inmaterial of lens is2 × 108 m/s, the focallength of the lens is(1) 20 cm (2) 30 cm(3) 10 cm (4) 15 cm
Ans. [2]
Q.89 Themagneticfieldinatravellingelectromagneticwave has a peak value of 20 nT. The peakvalue of electric field strength is :(1) 6 V/m (2) 9 V/m(3) 12 V/m (4) 3 V/m
Ans. [1]
Q.90 Two short bar magnets of length 1 cm eachhave magnetic moments 1.20Am2 and 1.00Am2 respectively. They are placed on ahorizontal tableparallel to each otherwith theirN polespointing towards the South.Theyhavea common magnetic equator and are separatedby a distance of 20.0 cm. The value of theresultant horizontal magnetic induction at themidpoint O of the line joining their centres isclose to (Horizontal component of earth'smgnetic induction is 3.6 × 10–5 Wb/m2)(1) 2.56 × 10–4 Wb/m2
(2) 3.50 × 10–4 Wb/m2
(3) 5.80 × 10–4 Wb/m2
(4) 3.6 × 10–5 Wb/m2
Ans. [1]