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Prime Classes Pvt. Ltd. : Kabir Nagar, Durgakund, Varanasi
Jee-Main (2018)
PHYSICS 1. It is found that if a neutron suffers an elastic
collinear collision with deuterium at rest, fractional loss of its energy is pd; while for collision with carbon nucleus at rest, fractional loss of energy is pc. The values of prespectively: (1) (0, 0) (2) (0, 1) (3) (89, 28) (4) (28, 89)
Sol. Ans (3) Let initial speed of neutron is v0 and kinetic energy is K 1st collision
by momentum conservation
021210 vv2vmv2mvmv
by e = 1 012 vvv
3
vv;
3
v2v 0
10
2
Fractional loss = 20
2
020
mv2
1
3
vm
2
1mv
2
1
89.9
8Pd
2nd collision
By momentum conservation
210 mv12mvmv 021 vv12v
by e = 1 012 vvv
13
v11v;
13
v2v 0
10
2
Now fraction loss of energy
Kabir Nagar, Durgakund, Varanasi-05, Ph. (0542) – 2314896
Solution
Main (2018) CODE – B
It is found that if a neutron suffers an elastic collinear collision with deuterium at rest, fractional
; while for its similar collision with carbon nucleus at rest, fractional
. The values of pd and pc are
89)
and kinetic energy is K
169
48
mv2
1
13
v11m
2
1mv
2
1P
20
2
020e
2. The mass of a hydrogen molecule is 3.32 1023 hydrogen molecules strike, perof area 2 cm2 at an angle of 45º to the normal, and rebound elastically with a speed of 10pressure on the wall is nearly:(1) 2.35 102 N/m2 (3) 2.35 103 N/m2
Sol. Ans (3)
º45cosnmv2dt
dpF
Pressure Area
º45cosnmv2
A
F
4
32723
102
10103.3102
23 m/N1035.2 3. A solid sphere of radius r made of a soft material of
bulk modulus K is surrounded by a liquid in a cylindrical container. A massless piston of area a floats on the surface of the liquid, covering entire cross section of cylindrical container. When a mass placed on the surface of the piston to compress the liquid, the fractional decrement in the radius of the
sphree
r
dr, is:
(1) Ka3
mg
(3) mg
Ka
2314896
1
28.0169
48
The mass of a hydrogen molecule is 3.32 10—27 kg. If hydrogen molecules strike, per second, a fixed wall
at an angle of 45º to the normal, and rebound elastically with a speed of 103m/s, then the pressure on the wall is nearly:
(2) 4.70 102 N/m2 (4) 4.70 103 N/m2
º
2
1
A solid sphere of radius r made of a soft material of bulk modulus K is surrounded by a liquid in a cylindrical container. A massless piston of area a floats on the surface of the liquid, covering entire cross section of cylindrical container. When a mass m is placed on the surface of the piston to compress the liquid, the fractional decrement in the radius of the
(2) Ka
mg
(4) mg3
Ka
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Sol. Ans (1)
Bulk Modulus = strainvolumetric
stressvolumetric
V
dVa
mgK
)i(...KA
mg
V
dV
Volume of sphere 3R3
4V
Fractional change in volume ...(r
dr3
V
dV
Using sing equation (i) & (ii)
Ka3
mg
r
dr
Ka
mg
r
dr3
4. Two batteries with e.m.f. 12V and 13V are connected in parallel across a load resistor of 10resistances of the two batteries are 1respectively. The voltage across the load lies between:(1) 11.4V and 11.5V (2) 11.7V and 11.8V(3) 11.6V and 11.7V (4) 11.5V and 11.6V
Sol. Ans (4)
volt3
37
2
1
1
12
13
1
12
3
2
12
12req
Now its equivalent circuit is
32
37
3
210
3/37i
volt56.1132
37010
32
3710iV10
5. A particle is moving in a circular path of radius a under
the action of an attractive potential U
energy is:
Kabir Nagar, Durgakund, Varanasi-05, Ph. (0542) – 2314896
)ii...(
batteries with e.m.f. 12V and 13V are connected in . The internal
resistances of the two batteries are 1 and 2 respectively. The voltage across the load lies between:
11.7V and 11.8V 11.5V and 11.6V
volt
A particle is moving in a circular path of radius a under
2r2
k . Its total
(1) Zero
(3) 2a4
k
Sol. Ans (1)
3r
K
r
uF
Since it is performing circular motion
2
2
3
2
r
Kmv
r
K
r
mvF
Total energy = P.E. + K.E.
6. Two masses m1 = 5kg and minextensible string over a frictionless as shown in the figure. The coefficient of friction of horizontal surface is 0.15. The minimum weight m that should be put on top of m2 to stop the motion is:
(1) 43.3 kg (3) 18.3kg
Sol. Ans (4) 50 – T = 5 a
T – 0.15(m + 10)g = (10 + m)a a = 0 for rest 50 = 0.15(m + 10)10)
m3
1000)10m(
20
35
kg3.23m
7. If the series limit frequency of the Lyman series is vthen the series limit frequency of the Pfund series is:
(1) vL/16 (3) 25vL Sol. Ans 2
22
1
1
1
h
K
h
E
h
KL
2p
1
5
1
h
K
2314896
2
(2) 2a
k
2
3
(4) 2a2
k
Since it is performing circular motion
2
2
r2
Kmv
2
1.E.K
0r2
K
r2
K22
and m2 = 10kg, connected by an inextensible string over a frictionless pulley, are moving as shown in the figure. The coefficient of friction of horizontal surface is 0.15. The minimum weight m that
to stop the motion is:
(2) 10.3kg
(4) 27.3kg
0.15(m + 10)g = (10 + m)a
10
If the series limit frequency of the Lyman series is vL, then the series limit frequency of the Pfund series is:
(2) vL/25 (4) 16vL
2
1=
25
1
h
Kp
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8. Unpolarized light of intensity I passes through an ideal polarizer A. Another identical polarizer B is placed behind A. The intensity of light beyond B is found to be
2
I. Now another identical polarizer C is placed between
A and B. The intensity beyond B is now found to be
The angle between polarizer A and C is: (1) 45º (2) 60º (3) 0º (4) 30º
Sol. Ans 1
20 cosII
201 cos
2
II
212 cosII
400 cos2
I
8
I
2
1cos º45
9. An electron from various excited states of hydrogen atom emit radiation to come to the ground state. Let g be the Broglie wavelength of the electron in the nstate and the ground state respectively. Let wavelength of the emitted photon in the transition from the nth state to the ground state. For large n, (A, B are constants):
(1) 2n
2n BA (2) 2
n
(3) 2n
n
BA
(4) n A
Sol. Ans (3)
2n
2g
2gx
11
m2
h
hchcEEE
2
2g
2n
2
2n
2g B
A
m2
h
..hc
10. The reading of the ammeter for a silicon diode in the given circuit is:
(1) 11.5 mA (2) 13.5 mA(3) 0 (4) 15 mA
Sol. Ans (1) For silicon 7.0Vb
A200
3.2A
200
7.03i
mA5.11mA200
2300
Kabir Nagar, Durgakund, Varanasi-05, Ph. (0542) – 2314896
Unpolarized light of intensity I passes through an ideal polarizer A. Another identical polarizer B is placed behind A. The intensity of light beyond B is found to be
. Now another identical polarizer C is placed between
intensity beyond B is now found to be 8
I.
º
An electron from various excited states of hydrogen atom emit radiation to come to the ground state. Let n,
be the Broglie wavelength of the electron in the nth state and the ground state respectively. Let n be the wavelength of the emitted photon in the transition from
state to the ground state. For large n, (A, B are
nBA
The reading of the ammeter for a silicon diode in the
13.5 mA
11. An electron, a proton and an alpha particle having the same kinetic energy are moving in circular orbital of radii re, rp, r respectively in a uniform magnetic field B. The relation between re, rp, p
(1) re < rp < r (3) re > rp = r
Sol. Ans. (4)
2
Km2R ,
e
Km2R
e
e
e
km2
e2
m4K2R
pp
RRR pe
12. A parallel plate capacitor of capacitance 90 pF is connected to a battery of emf 20V. If a dielectric
material of dielectric constant
between the plates, the magnitude of the induced charge will be: (1) 2.4 nC (3) 1.2 nC
Sol. Ans. (3)
K
11QQb
5
311020
3
590 12
5
106
5
2103000
912
13. For an RLC circuit driven with voltage of
and frequency LC
10
resonance. The quality factor, Q is given by:
(1) )C
R
0
(3) R
L0
Sol. Ans. (3)
Quality factor
0)(
Where, L
R
R
LQ 0
14. A telephonic communication carrier frequency of 10GHz. Only 10% of it is utilized for transmission. How many telephonic channels cantransmitted simultaneously if each channel requires a bandwidth of 5 kHz:
(1) 2 105
(3) 2 103
2314896
3
An electron, a proton and an alpha particle having the same kinetic energy are moving in circular orbital of
respectively in a uniform magnetic field B.
is: (2) re < r < rp (4) re < rp = r
,
e
Km2R
p
p
A parallel plate capacitor of capacitance 90 pF is connected to a battery of emf 20V. If a dielectric
material of dielectric constant 3
5K is inserted
between the plates, the magnitude of the induced charge
(2) 0.9 nC (4) 0.3 nC
nC2.1C
For an RLC circuit driven with voltage of amplitude vm
LC
1the current exhibits
resonance. The quality factor, Q is given by:
(2) 0
CR
(4) L
R0
A telephonic communication service is working at carrier frequency of 10GHz. Only 10% of it is utilized for transmission. How many telephonic channels can be transmitted simultaneously if each channel requires a
(2) 2 106
(4) 2 104
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Sol. Ans. (1)
Utilized frequency GHz110
10
Band width = 5KH
No. channels = 3
9
105
101
widthBand
Range
15. A granite rod of 60cm length is clamped at its middle point and is set into longitudinal vibrations. The densityof granite is 2.7 103 kg/m3 and its Young’s modulus is 9.27 1010 Pa. What will be the fundamental frequency of the longitudinal vibrations: (1) 10 kHz (2) 7.5 kHz(3) 5 kHz (d) 2.5 kHz
Sol. Ans. (3)
Wave velocity (v) =
Y3
10
107.2
1027.9
0
0
V
5K Hz
16. Seven identical circular planar disks, each of mass M and radius R are welded symmetrically as shown. The moment of inertial of the arrangement about the axis normal to the plane and passing through the point P is:
(1) 2MR2
73 (2) MR
2
181
(3) 2MR2
19 (4) MR
2
55
Sol. Ans. (2) M.I. about required axis
2cm mdII
222 )R3(m7])R2(m[6mR2
7
222 mR63mR24mR2
7
2mR2
181I
17. Three concentric metal shells A, B and C of respective radii, a, b and c (a < b < c) have surface charge densities +, – and + respectively. The potential of shell B is:
(1)
a
b
cb 22
0
(2)
b2
0
(3)
c
a
ba 22
0
(4)
a 2
0
Kabir Nagar, Durgakund, Varanasi-05, Ph. (0542) – 2314896
5102
A granite rod of 60cm length is clamped at its middle point and is set into longitudinal vibrations. The density
and its Young’s modulus is Pa. What will be the fundamental frequency
(2) 7.5 kHz (d) 2.5 kHz
10
Seven identical circular planar disks, each of mass M symmetrically as shown. The
moment of inertial of the arrangement about the axis normal to the plane and passing through the point P is:
2MR
2MR
Three concentric metal shells A, B and C of respective radii, a, b and c (a < b < c) have surface charge densities
respectively. The potential of shell B is:
a
c
c2
c
b
b2
Sol. Ans. (4) Potential of shell of Radius b
c
q
b
q
b
qKV CBA
c
q
b
qqK CBA
4
b
b4a4
4
1 22
0
c
b
ba 22
0
18. In a potentiometer experiment, it is found that no current passes through the galvanometer when the terminals of the cell are connected across 52cm of the potentiometer wire. If the cell is shunted by a resistaof 5, a balance is found when the cell is connected across 40 cm of the wire. Find the internal resistance of the cell: (1) 2 (3) 1
Sol. Ans. (4) 52 ….(1) : potential gradient
40r
5r… (2)
40
5r
5
52
40
5r
5
200r40260
5.12
3r
19. An EM wave from air enters a medium. The electric
fields are
2cosxEE 011
)]ctz2(kcos[xEE 02
in medium, where the wave
number k and frequency v refer to their values in air. The medium is non-magnetic. If
relative permittivities of air and medium respectively, which of the following is corr
(1) 4
1
2
1
r
r
(3) 42
1
r
r
Sol. Ans. (1)
t2
c
2.zcosEE i01
CKtzK2cosEE2o2
Frequency of light =
2314896
4
Potential of shell of Radius b
c
c4 2
In a potentiometer experiment, it is found that no current passes through the galvanometer when the terminals of the cell are connected across 52cm of the potentiometer wire. If the cell is shunted by a resistance
, a balance is found when the cell is connected across 40 cm of the wire. Find the internal resistance of
(2) 2.5 (4) 1.5
: potential gradient
An EM wave from air enters a medium. The electric
t
c
zv2 in air and
in medium, where the wave
number k and frequency v refer to their values in air. magnetic. If
1r and
2r refer to
relative permittivities of air and medium respectively, which of the following is correct:
(2) 2
1
2
1
r
r
(4) 22
1
r
r
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Wavelength
C
)( o
KK2
2
20
2
2
1
1
221
1
4
1
2
1
20. The angular width of the centre maximum in a single slit diffraction pattern is 60º. The width of the slit is 1m. The slit is illuminated by monochromatic plane waves. If another alit of same width is made near it, Young’s fringes can be observed on a screen placed at a distance 50 cm from the slits. If the observed fringe width is 1cm, what is slit separation distance: (1) 75m (b) 100 m(3) 25 m (d) 50 m
Sol. Ans. (3)
2
sinb
m2
1130sinb
Fringe width : d
D
d
1050105.0m10
262
6105.2d
m25d
21. A silver atom in a solid oscillates in simple harmonic motion in some direction with a frequency of 10What is the force constant of the bonds connecting one atom with the other (Mole wt of silver = 108 and Avagadro number = 6.02 1023 gm mole(1) 2.2 N/m (2) 5.5 N/m(3) 6.4 N/m (4) 7.1 N/m
Sol. Ans. (4)
m
Kn2
mn4K 20N
mm
23
324
1002.6
10810108.94
.7
22. From a uniform circular disc of radius R
a small disc of radius 3
R removed as shown in the
figure. The moment of inertia of the remaining disc about an axis perpendicular to the plane of the disc and passing through centre of the disc is:
Kabir Nagar, Durgakund, Varanasi-05, Ph. (0542) – 2314896
The angular width of the centre maximum in a single slit diffraction pattern is 60º. The width of the slit is
m. The slit is illuminated by monochromatic plane waves. If another alit of same width is made near it, Young’s fringes can be observed on a screen placed at a distance 50 cm from the slits. If the observed fringe
ance: m
oscillates in simple harmonic motion in some direction with a frequency of 1012/sec. What is the force constant of the bonds connecting one atom with the other (Mole wt of silver = 108 and
gm mole—1): ) 5.5 N/m ) 7.1 N/m
m/N1.
circular disc of radius R and mass 9M,
as shown in the
figure. The moment of inertia of the remaining disc about an axis perpendicular to the plane of the disc and
(1) 10 MR2
(3) 4 MR2
Sol. Ans. (3) Moment of inertial of remaining disc
22 2m
3
R
2
m
2
qmRI
9
mR4
18
mR
2
qmR 222
222
2
mR9
18
qmR
2
mR9
23. In a collinear collision, a particle with an initial speed v0 strikes a stationary particle of the same mass. If the final total kinetic energy is 50% greater than the original kinetic energy, the magnitude of the relative velocity between the two particles, after collision, is:
(1) 2
v0
(3) 4
v0
Sol. Ans. (4)
After collision
20
22
21
4
1mv
2
1mv
2
1mv
2
1
20
22
21 v
2
3vv
021 vvv 221 )vv(
20
2021 v
2
3vvv2 v2 1
2
vv
2
3)vv(
202
02
21 v(
24. The dipole moment of a circular loop carrying a current I, is m and the magnetic field at the centre of the loop is B1. When the dipole moment is doubled by keeping the current constant, the magnetic field at t
loop is B2. The ratio 2
1
B
Bis:
(1) 2
(3) 2
2314896
5
(2) 2MR9
37
(3) 2MR9
40
Moment of inertial of remaining disc
2
3
R2
22
mR42
mR
In a collinear collision, a particle with an initial speed a stationary particle of the same mass. If the
final total kinetic energy is 50% greater than the original kinetic energy, the magnitude of the relative velocity between the two particles, after collision, is:
(2) 2
v0
(4) 0v2
20mv
4
1
20v
2
vv
20
2
021 v2)vv
circular loop carrying a current I, is m and the magnetic field at the centre of the loop is
. When the dipole moment is doubled by keeping the current constant, the magnetic field at the centre of the
(2) 2
1
(4) 3
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Sol. Ans. (1)
Magnetic Moment (m) = i : 2R
R2
iB 0
1
22 .iRi.2'R.m2
New radius of loop is R2'R
R22
iB 0
2
2B
B
2
1
25. The density of a material in the shape of a cube is determined by measuring three sides of the cube and its mass. If the relative error in measuring the mass and length are respectively 1.5% and 1%, the maximum error in determining the density is: (1) 4.5% (2) 6% (3) 2.5% (4) 3.5%
Sol. Ans. (1)
3a
m
% error in = % error in m + 3 % error in length = 1.5 + 3 1 = 4.5% 26. On interchanging the resistance, the balance point of a
metre bridge shifts to the left by 10 cm. The resistance of their series combination is 1 k . Howresistance on the left slot before interchanging the resistances: (1) 550 (2) 910 (3) 990 (4) 505
Sol. Ans. (1) On interchanging the resistance shifting is 10cm.
Therefore, –10 = 100 – 551102
1000RR9
11
45
55
R
R21
2
1
1150R1000R11
9R 111 R
27. In an a.c. circuit, the instantaneous e.m.f. and current are given by
e = 100 sin 30t
30sin20i
In one cycle of a.c., the average power consumed by the circuit and the wattles current are, respectively:
(1) 0,2
50 (2) 50, 0
Kabir Nagar, Durgakund, Varanasi-05, Ph. (0542) – 2314896
2'R
The density of a material in the shape of a cube is sides of the cube and its
in measuring the mass and length are respectively 1.5% and 1%, the maximum
% error in length
, the balance point of a metre bridge shifts to the left by 10 cm. The resistance
How much was the resistance on the left slot before interchanging the
On interchanging the resistance shifting is 10cm.
550R1
In an a.c. circuit, the instantaneous e.m.f. and current
4t30
e power consumed by the circuit and the wattles current are, respectively:
(3) 50, 10
Sol. Ans. (4)
cos2
10020cos
2
viP 00
avg
sinii rms
28. All the graphs below are intended to represent the same motion. One of them does it incorrectly. Pick it up:
Sol. Ans. (1) Position time graph is parabolic opening downward. Velocity time graph will be straight line with (
slope and velocity position graph will be parabola on –5 axis.
Distance time graph is incorrect. 29. Two moles of an ideal monoatomic gas occupies a
volume V at 27ºC. The gas expands adiabatically tovolume 2V. Calculate (a) the final temperature of (b) change in its internal energy:
(1) (a) 189K (b) –27kJ (3) (a) 189K (b) 2.7kJ Sol. Ans. (1) For adiabatic process
.constTV 1
1g
22
1
11 VTVT
3
5
23/2
23/2 T)V2(TV300
30. A particle is moving with a uniform speed in a circular orbit of radius R in a central force inversely proportional to the nth power of R. If the period of rotation of the particle is T, then:
(a) T 2/)R 1n(
(c) T 2/3R for any n Sol. Ans. (1)
n
2
n R
K
R
mv
R
KF
1n CRmRK
R2
V
R2T
2314896
6
(4) 10,2
1000
º45cos2
1000 ,
intended to represent the same motion. One of them does it incorrectly. Pick it up:
Position time graph is parabolic opening downward. Velocity time graph will be straight line with (–)ve
slope and velocity position graph will be parabola on
Distance time graph is incorrect. Two moles of an ideal monoatomic gas occupies a volume V at 27ºC. The gas expands adiabatically to a volume 2V. Calculate (a) the final temperature of (b)
(2) (a) 195K (b) 2.7 kJ
(4) (a) 195K (b) –2.7k
3
5
3/22
300 and TnR
2
3U
A particle is moving with a uniform speed in a circular orbit of radius R in a central force inversely
power of R. If the period of rotation of the particle is T, then:
(b) T 2/nR
(d) T 1
2
n
R
1nmR
KV
2/)1n(R.CR
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2/)1n(2
21n
CRTCRT
T 2/)1n(R MATHEMATICS
31. If the tangent at (1, 7) to the curve x2 = y the circle x2 +y2 + 16x + 12y+c = 0 then the value of c is: (1) 85 (2) 95 (3) 195 (4) 185
Sol. Ans. (2)
Equation of tangent 62
)7y(1.x
2x – y + 5 = 0
By using condition of tangency for circle
We get c = 95 32. If L1 is the line of intersection of the planes
2x – 2y + 3z – 2 = 0, x – y + z + 1 = 0 and Lline of intersection of the planes x + 2y 3x – y + 2z – 1 = 0, then the distance of the origin from the plane, containing the lines L1 and L2
(1) 22
1 (2)
2
1
(3) 24
1 (4)
23
1
Sol. Ans. (4) Equation of required plane
)1zyx(2z3y2x2P
z)3(y)2(x)2(P
To find direction cosines of line L2 a + 2b – c = 0 3a – b + 2c = 0
13
21
c
32
11
b
21
12
a
7
c
5
b
3
a
Plane P contains line L2, therefore
0)3(7)2(5)2(3
5
Equation of plane is 7x – 7y + 8z + 3 = 0
Length of perpendicular = 877
000
22
33. If C, are the distinct roots, of the equation
1071012 then,01xx is equal to:
(1) 1 (2) 2 (3) – 1 (4) 0
Sol. Ans. (1)
2,
Kabir Nagar, Durgakund, Varanasi-05, Ph. (0542) – 2314896
= y – 6 touches the circle x2 +y2 + 16x + 12y+c = 0 then the value of c
By using condition of tangency for circle p = r
is the line of intersection of the planes y + z + 1 = 0 and L2 is the
line of intersection of the planes x + 2y – z – 3 = 0, 1 = 0, then the distance of the origin from
is:
Equation of required plane
0
02
7y + 8z + 3 = 0
23
1
8
3
2
are the distinct roots, of the equation
is equal to:
1072101 )()( ( 2
34. Tangents are drawn to the hyperbola
the points P and Q. If these tangents intersect at the point T(0, 3) then the area (in sq. units) of
(1) 360
(3) 545
Sol. Ans. (3)
136
y
9
x 22
Equation of chord of contact PQ is y + 12 = 0 To find P and Q solve y + 12 = 0
and 36yx4 22
)12,53(P
)12,53(Q
Area TSPQ2
1a
15562
1 = 545
35. If the curves y2 = 6x, 9x2 + byat right angles, then the value of b is:
(1) 4
(3) 6
Sol. Ans. (2)
Point of intersection ),(
y2 = 6x
y
3
dx
dy
3
dx
dy),(
16y6x9 22
b
9
dx
dy),(
1b
93
put 62 b = 9/2
36. If the system of linear equations x + ky + 3z = 0 3x + ky – 2z = 0 2x + 4y – 3z = 0
has a non-zero solution (x, y, z) then
(1) – 30 (3) – 10
2314896
7
) = 1
Tangents are drawn to the hyperbola 36yx4 22 at
the points P and Q. If these tangents intersect at the point T(0, 3) then the area (in sq. units) of PTQ is:
(2) 536
(4) 354
Equation of chord of contact PQ is y + 12 = 0 To find P and Q solve y + 12 = 0
+ by2 = 16 intersect each other at right angles, then the value of b is:
(2) 2
9
(4) 2
7
(say)
If the system of linear equations
zero solution (x, y, z) then 2y
xz is equal to:
(2) 30 (4) 10
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Sol. Ans. (4) For non zero solution 0
0
342
2K3
3K1
k = 11
Now equations x + 11y + 3z = 0 ………..(i) 3x + 11y – 2z = 0 ……….(ii) 2x + 4y – 3z = 0 ……….(iii) (i) and (ii) - 2x + 5z = 0
5z = 2x z2
5x
From (iii) 0z3y4z2
52
2z + 4y = 0
Z + 2y = 0 2
zy
Now 2y
xz104
2
5
4
z
zz2
5
2
37. Let 0x:Rx{S and
}.06)6x(x3x2 Then S :
(1) Contains exactly two elements (2) Contains exactly four elements (3) Is an empty set (4) Contains exactly one element
Sol. Ans. (1) 0x
06)6x(x3x2
Case-I : x [9, ]
06x6x)3x(2
0x4x x = 0 (rejected), x = 16 Case-II x [0, 9]
06x6x)x3(2
0)2x()6x(
x = 36 (rejected), x = 4 exactly two elements S = {4, 16} 38. If sum of all the solutions of the equation
12
1x
6cos.x
6cos.xcos8
,k then k is equal to:
(1) 9
8 (2)
9
20
Kabir Nagar, Durgakund, Varanasi-05, Ph. (0542) – 2314896
………..(i) ……….(ii) ……….(iii)
Then S :
If sum of all the solutions of the equation
1 in ],0[ is
(3) 3
2
Sol. Ans. (4)
sinxcos6
cos
xsin6
sinxcos6
cosxcos8
xsin4
1xcos
4
3xcos8 22
1)xsin41(xcos2 2
2
1)xcos43(xcos 2
2
1x3cos
9
7,
9
5,
9x
Sum of solutions =
k9
13
39. A bag contains 4 red and 6 black balls. A ball is drawn
at random from the bag, its colour is observed and this
ball along with two additional balls of the same colour
are returned to the bag. If now a ball is drawn at random
from the bag, then the probability that this drawn ball is
red, is:
(1) 5
1
(3) 10
3
Sol. Ans. (4)
red4
P (Red in IInd drawn) = P(Red in second drawn if in I
drawn black in observed )
+ P(Red in II
drawn red in observed )
=
1
1
21
B
RP).B(P
R
RP).R(P
=12
4
10
6
12
6
10
4 =
5
2
120
48
2314896
8
(4) 9
13
12
1xsin
6sin
x
12
1
= 9
13k
A bag contains 4 red and 6 black balls. A ball is drawn
at random from the bag, its colour is observed and this
ball along with two additional balls of the same colour
bag. If now a ball is drawn at random
from the bag, then the probability that this drawn ball is
(2) 4
3
(4) 5
2
black6
drawn) = P(Red in second drawn if in Ist
+ P(Red in IInd drawn if in Ist
1
2
B
R
5
2
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40. Let ,x
1x)x(gand
x
1x)x(f
2
2
}1,0,1{Rx . If ,)x(g
)x(f)x(h then the local
minimum value of h(x) is:
(1) 22 (2) 22 (3) 3 (4) – 3 Sol. Ans. (2)
x/1x
x/1x)x(h
22
x
1x
2
x
1x)x(h
22
x
1x
21
x
11)x('h
For maxima and minima h’(x) = 0
2x
1x
h’(x) changes its sign from (-)ve to (+)ve at
2x
1x
therefore local minimum value of
222
22)x(h
41. Two sets A and B are as under:
5band15a:RR)b,a{(A
)5b(9)6a(4:RR)b,a{(B 22
(1) BA (an empty set)
(2) neither ABnorBA
(3) AB (4) BA Sol. (4) band)6,4(a:RR)b,a{(A
for B
14
)5b(
9
)6a( 22
Put a – 6 = x and b – 5 = y yand)0,2(x:RR)y,x{(A
B
14
y
9
x:}RR)y,x(
22
BA
Kabir Nagar, Durgakund, Varanasi-05, Ph. (0542) – 2314896
then the local
)ve to (+)ve at
therefore local minimum value of
}1
}362 . Then:
)}6,4(
)}1,1( &
42. The Boolean expression
equivalent to: (1) q (3) ~ p
Sol. Ans. (3) )qp(~)qp(~
)qp(~)q~p(~
)qq(~p~ p~
43. Tangent and normal are drawn at P(16, 16) on the parabola y2 = 16x, which intersect the axis of the parabola at A and B, respectively. If C is the centre of the circle through the points P, A and B and
,CPB then value of tan
(1) 3
(3) 2
1
Sol. Ans. (4) Equation of tangent
2
16x1616.y
x – 2y + 16 = 0 Equation of normal y – 16 = - 2x + y – 48 = 0 A : (-16, 0), B : (24, 0)
516AP
58BP
AB = 40 APB is a right angle triangle
3
4
416
016mCP
22416
016mBP
2m.m1
mmtan
BPCP
BPCP
44. If A(
4xx2x2
x24xx2
x2x24x
ordered pair (A, B) is equal to: (1) (-4, 5) (3) (-4, -5)
Sol. Ans. (1) To find A, put x = 0 A = - 4
2314896
9
The Boolean expression )qp(~)qp(~ is
(2) ~q (4) p
Tangent and normal are drawn at P(16, 16) on the = 16x, which intersect the axis of the
parabola at A and B, respectively. If C is the centre of the circle through the points P, A and B and
tan is:
(2) 3
4
(4) 2
-2(x - 16)
APB is a right angle triangle
,)Ax()BxA 2 then the
ordered pair (A, B) is equal to: (2) (4, 5) (4) (-4, 3)
4
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To find B, first differentiate and then put x = 0 B = 5 45. The sum of the co-efficient of all odd degree terms in
the expansion of
)1x(,1xx1xx5
35
3
(1) 1 (2) 2 (3) – 1 (4) 0
Sol. Ans. (2) Using (x +a)5 + (x -a)5
]a.xCa.xCxC[2 44
5232
550
5
53
53 1xx1xx
x(xC)1x(xCxC[2 34
5332
550
5
5x10x5x10x10x[2 47365
Considering odd degree terms,
]x5x10x5x[2 375
sum of coefficient of odd terms is 2 46. Let a1, a2, a3,…,a49 be in A.P. such that
.66aaand416a 439
12
0k1k4
,m140a...aa 217
22
21 then m is equal to:
(1) 34 (2) 33 (3) 66 (4) 68
Sol. Ans. (1)
416a12
0K1k4
416]d48a2[2
131
32d24a1 …………..(1)
66d50a266aa 1439 …………..(2)
64d48a2 1 by …………..(1)
d = 1 and a1 = 8
17
1r
17
1r
22r ]1).1r(8[am140
17
1r
2)7r(m140
24
1r
2rm140
6
15.8.7
6
49.25.24m140
]3105[6
5.8.7m140 280m140
47. A straight line through a fixed point (2, 3) intersect the coordinates axes at distinct points P and Q. If O is the origin and the rectangle OPRQ is completed, then the locus of R is: (1) 3x + 2y = xy (2) 3x + 2y = 6xy(3) 3x + 2y = 6 (4) 2x + 3y = xy
Sol. Ans. (1) Equation of line
Kabir Nagar, Durgakund, Varanasi-05, Ph. (0542) – 2314896
To find B, first differentiate and then put x = 0
efficient of all odd degree terms in
) is:
])1 23
]x5
be in A.P. such that
If
then m is equal to:
…………..(1)
…………..(2)
by …………..(1)
7
1r
2r
34m17.280
line through a fixed point (2, 3) intersect the coordinates axes at distinct points P and Q. If O is the origin and the rectangle OPRQ is completed, then the
(2) 3x + 2y = 6xy (4) 2x + 3y = xy
y – 3 = m (x - 2)
0,
m
3m2:P ,
)m23,0(:Q
m
3m2h
k = 3 – 2m Eliminate ‘m’ hK = 3h + 2K 3x + 2y = xy
48. The value of dx21
xsin2
2
x
2
is:
(1) 4
(3) 8
Sol. Ans. (2)
2/
2/x
2
dx21
xsin
Using property fdx)x(fb
a
b
a
dx21
xsinI
2/
2/x
2
dx21
xsin2I
2/
2/x
2x
(i) + (ii)
2/
2/
2 dxxsinI2
2I2
49. Let x)x(f,xcos)x(g 2
roots of the quadratic equation Then the area (in sq. units) bounded by the curve
)x)(f0g(y and the lines x
(1) )23(2
1
(3) )13(2
1
Sol Ans. (3)
0x9x18 22
3/,6/
3/
6/
dxxcosA 3(2
1A
50. For each ,Rt let [t] be the greatest integer less than
or equal to t. Then
2314896
10
………(i)
………(ii)
is:
(2) 4
(4) 2
………(i)
dx)xba(f
………(ii)
2/
0
2 dxxsin 4/I
,x and )(, be the
roots of the quadratic equation .0x9x18 22 Then the area (in sq. units) bounded by the curve
,0yandx,x is:
(2) )12(2
1
(4) )13(2
1
)13
let [t] be the greatest integer less than
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x
15....
x
2
x
1xlim
0x
(1) is equal to 120 (2) does not exist (in R) (3) is equal to 0 (4) is equal to 15 Sol. Ans. (1)
x
1xlim
0x
x
1
x
11
x
1
1x
1xx1
1limx
1xlimx1lim
0x0x0x
1x
1xlim
0x
Similarly 2x
2xlim
0x
Ans. 1 +2+3+….+ 15 = 120
51. If
9
1i
2i
9
1ii ,45)5x(and9)5x( then the standard
deviation of the 9 items x1, x2,..,x9 is: (1) 2 (2) 3 (3) 9 (4) 4
Sol Ans. (1)
2
i2
iD
9
)5x(
9
)5x(S
29
36
52. The integral
xcosxsinxsinxcosx(sin
xcosxsin23235
22
is equal to:
(1) Cxcot1
13
(2) cot1
13
(3) C)xtan1(3
13
(4) tan1(3
1
(where C is a constant of integration ) Sol. Ans. (4)
xcosxsinxsinxcosx(sin
xcosxsin23235
22
= dx)1xtanxtanx(tan
xsecxcosxsin2325
1022
dx)xtan1()xtan1(
xsecxsin2322
82
Kabir Nagar, Durgakund, Varanasi-05, Ph. (0542) – 2314896
(2) does not exist (in R) (4) is equal to 15
then the standard
2
9
9
9
45
dx
)xcos 25
Cx3
C)xtan
13
dx)xcos 25
dx)xtan1(xsec
xsecxtan234
62
dx)xtan1(
xsecxtan23
22
txtan1 3
dtxdxsec.xtan3 22
2t
dt
3
1c
)xtan1(3
13
53. Let x)x(f:Rt{S
differentiable at t}. Then the set S is equal to:(1) }{
(3) (an empty set)
Sol. Ans (3)
xsin)1e(x)x(fx
We check differentiability at
xat
R.H.D. = e(h
lim0h
= 0
L.H.D. = e(h
lim0h
= 0 RHD = LHD so function is differentiable at x at x = 0
h
)1e(hlimD.H.R
h
0h
h
e(hlimD.H.L
h
0h
RHD = LHD so function is differentiable at x = 0 set S is empty set,
54. Let y= y(x) be the solution of the differentiable equation
0(x,x4xcosydx
dyxsin
If ,02
y
then
6y is equal to:
(1) 2
9
8
(3) 2
39
4
Sol. Ans. (1) xdx4dxcosyxdysin
dxx4)xsiny( '
2314896
11
c
xsin)1e(.x
is not
differentiable at t}. Then the set S is equal to: (2) },0{
(4) {0}
We check differentiability at 0xandx
h
0hsin)1h
h
0hsin)1h
RHD = LHD so function is differentiable
00hsin)
0h
0hsin)1
RHD = LHD so function is differentiable at x = 0
Let y= y(x) be the solution of the differentiable equation
).,0
is equal to:
(2) 2
9
4
(4) 2
39
8
),0(x
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dxx4)'xsiny(
cx2xsiny 2 …………..(1)
02
y
2
c2
From (1) 2
x2xsiny2
2
6y
55. Let u
be a vector coplanar with the vectors
.kjbandkj3i2a
If u
is perpendicular to
,24b.uanda
then 2
u
is equal to:
(1) 256 (2) 84 (3) 336 (4) 315
Sol. Ans. (3)
)kj(y)kj3i2(xu
k)xy(j)yx3(ix2u
0a.u
7x + y = 0 ………..(i)
24b.u
x + y = 12 ………(ii) on solving (i) and (ii) x = -2, y = 14
336u2
56. The length of the projection of the line segment joining the points (5, -1, 4) and (4, -1, 3) on the plane , x + y + z = 7 is:
(1) 3
1 (2)
3
2
(3) 3
2 (4)
3
2
Sol. Ans. (2) Foot of perpendicular drawn from (5, 1, 4)
222
11
111
)7415(
1
4
1
1
1
5
3
11,
3
4,
3
14111
Foot of perpendicular drawn from (4, -1, 3)
222
222
111
314(4
1
3
1
1
1
4
3
10,
3
2,
3
13222
Length of projection
221
221
221 )()()(
57. PQR is a triangular park with PQ = PR = 200m. A T.V. tower stands at the mid-point of QR. If the angle of
Kabir Nagar, Durgakund, Varanasi-05, Ph. (0542) – 2314896
…………..(1)
9
8 2
be a vector coplanar with the vectors
is perpendicular to
………..(i)
………(ii)
The length of the projection of the line segment joining 1, 3) on the plane , x + y + z
Foot of perpendicular drawn from (5, 1, 4)
)
1, 3)
2
)7
3
2
PQR is a triangular park with PQ = PR = 200m. A T.V. point of QR. If the angle of
elevation of the top of the tower at P, Q and R are respectively 45º, 30º and 30º, then the height of the tower (in m) is:
(1) 3100
(3) 100
Sol. Ans. (3)
Let height of tower MN is ‘h’ in QMN
030tanQM
MN
MRh3QM
Now in MNP MN = PM In PMQ
22 )h3()200(MP
From (2)
hh)h3()200( 22
58. From 6 different novels and 3 different dictionaries, 4 novels and 1 dictionary are to be selected and arranged in a row on a shelf so that the dictionary is always in the middle. The number of such arrangement is: (a) at least 500 but less than 750(b) at least 750 but less than 1000(c) at least 1000 (d) less than 500
Sol. Ans. (3)
1CC 13
46 4 = 1080
Answer will be at least 1000 59. Let A be the sum of the first 20 terms and B be the sum
of the first 40 terms of the series
254.232.21 22222 If B – 2A = 100 , then is equal to:
(1) 464 (3) 232 Sol. Ans. (4)
54.232.21 22222
)19....31(SA 22220
)20....321( 2222
= 6
211110(2
6
412120 2
= 20774170
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12
elevation of the top of the tower at P, Q and R are respectively 45º, 30º and 30º, then the height of the
(2) 250
(4) 50
of tower MN is ‘h’
………….(1)
…………..(2)
m100
From 6 different novels and 3 different dictionaries, 4 novels and 1 dictionary are to be selected and arranged in a row on a shelf so that the dictionary is always in the middle. The number of such arrangement is: (a) at least 500 but less than 750 (b) at least 750 but less than 1000
Let A be the sum of the first 20 terms and B be the sum of the first 40 terms of the series
....6.2 2 is equal to:
(2) 496 (4) 248
....6.2 2
)20...42.(2 222
)20......42( 222
)21
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42(.2)39.....31(SB 222240
41740274120 70241740274120A2B
)77287(40)140540(41 = 16400 + 8400
= 24810024800
60. Let the orthocentre and centroid of a triangle be A(
and B(3, 3) respectively. If C is the circumcentre of this triangle, then the radius of the circle having line segment AC as diameter is:
(1) 2
53 (2)
2
53
(3) 10 (4) 102
Sol. Ans. (1)
612
323
12
523
A(-3, 5), C : (6, 2)
Radius = 2
53)25()36(
2
1 22
CHEMISTRY
61. Total number of lone pair of electrons in
(1) 9 (b) 12 (3) 3 (d) 6
Sol. Ans. (1) Total number of lone pair of electrons
in 3I is 9
62. Which of the following salts is the most basic in
aqueous solution: (1) FeCl3 (2) Pb(CH3
(3) Al(CN)3 (4) CH3COOKSol. Ans. (4)
63. Phenol reacts with methyl chloroformate in the presence
of NaOH to form product A. A reacts with Brproduct B. A and B are respectively:
(1) (2)
Kabir Nagar, Durgakund, Varanasi-05, Ph. (0542) – 2314896
)40...4 22
77404170 = 16400 + 8400
Let the orthocentre and centroid of a triangle be A(-3, 5) and B(3, 3) respectively. If C is the circumcentre of this triangle, then the radius of the circle having line
2
Total number of lone pair of electrons in 3I is:
Which of the following salts is the most basic in
3COO)2 COOK
reacts with methyl chloroformate in the presence
of NaOH to form product A. A reacts with Br2 to form
(3)
(4)
Sol. Ans. (1) 64. The increasing order of basicity of the following
compounds is:
(1) (b) < (a) < (d) < (c) (3) (a) < (b) < (c) < (d)
Sol. Ans. (1)
65. An alkali is titrated against an acid with methyl orange
an indicator, which of the following is a correct combination: Base Acid (1) Weak Strong (2) Strong Strong (3) Weak Strong (4) Strong Strong
Sol. (1)
2314896
13
The increasing order of basicity of the following
(b) (d) < (b) < (a) < (c) (d) (b) < (a) < (c) < (d)
An alkali is titrated against an acid with methyl orange an indicator, which of the following is a correct
End point Yellow to pinkish red Pink to colourless
Colourless to pink Pinkish red to yellow
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66. The trans-alkenes are formed by the reduction of
alkynes with: (1) Na/liq. NH3 (2) Sn – HCl (3) H2 – Pd/C, BaSO4 (4) NaBH4
Sol. Ans. (1)
67. The ratio of mass percent of C and H of an organic
compound (CXHYOZ) is 6 : 1. If one molecule of the above compound (CXHYOZ) contains half as much oxygen as required to burn one molecule CXHY completely to CO2 and H2O. The empirical formula of compound CXHYOZ is: (1) C3H4O2 (2) C2H4O3
(3) C3H6O3 (4) C2H4O Sol. Ans (2)
Kabir Nagar, Durgakund, Varanasi-05, Ph. (0542) – 2314896
alkenes are formed by the reduction of
HCl
The ratio of mass percent of C and H of an organic
) is 6 : 1. If one molecule of the ) contains half as much
oxygen as required to burn one molecule of compound O. The empirical
3
68. Hydrogen peroxide oxidizes
36 ])CN(Fe[ in acidic medium but reduces
36 ])CN(Fe[ to 4
6 ])CN(Fe[
other products formed are respectively:(1) H2O and (H2O + O2)
(2) H2O and (H2O + OH ) (3) (H2O + O2) and H2O
(4) (H2O + O2) and (H2O + OH
Sol. Ans. (1)
69. The major product formed in the following reaction is:
(1) (3) Sol. Ans. (2)
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14
Hydrogen peroxide oxidizes 4
6 ])CN(Fe[ to
in acidic medium but reduces
in alkaline medium. The
other products formed are respectively:
OH )
The major product formed in the following reaction is:
(2)
(4)
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70. How long (approximate) should water be electrolysed
by passing through 100 amperes current so that the oxygen released can completely burn 27.66g of diborane (Atomic weight of B = 10.8u): (1) 3.2 hours (2) 1.6 hours(3) 6.4 hours (4) 0.8 hours
Sol. Ans. (1)
71. Which of the following lines correctly show the
temperature dependence of equilibrium an exothermic reaction:
(1) C and D (2) A and D(3) A and B (4) B and C
Sol. Ans. (3)
72. At 518ºC, the rate of decomposition of a sample of
gaseous acetaldehyde, initially at a pressure of 363 Torr, was 1.00 Torr s—1 when 5% had reacted and 0.5
Kabir Nagar, Durgakund, Varanasi-05, Ph. (0542) – 2314896
How long (approximate) should water be electrolysed by passing through 100 amperes current so that the oxygen released can completely burn 27.66g of
(2) 1.6 hours (4) 0.8 hours
Which of the following lines correctly show the temperature dependence of equilibrium constant, K, for
(2) A and D (4) B and C
At 518ºC, the rate of decomposition of a sample of gaseous acetaldehyde, initially at a pressure of 363
when 5% had reacted and 0.5
Torr s—1 when 33% had reacted. The order of the reaction is: (1) 1 (3) 2
Sol. Ans. (3)
73. Glucose on prolonged heating with HI gives:
(1) Hexanoic acid (3) n-Hexane
Sol. Ans. (3)
74. Consider the following reaction and statements:
243 Co[Br]Br)NH(Co[
(1) III and IV (3) I and II Sol. Ans. (4)
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when 33% had reacted. The order of the
(2) 0 (4) 3
Glucose on prolonged heating with HI gives:
(2) 6-iodohexanal (4) 1-Hexane
Consider the following reaction and statements:
3333 NH]Br)NH(Co
(2) II and IV
(4) I and III
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75. The major product of the following reaction is:
(1) (2)
(3) (4) Sol. Ans. (4)
76. Phenol on treatment with CO2 in the presence of NaOH
followed by acidification produces compound X as the major product. X on treatment with (CHpresence of catalytic amount of H2SO4 produces:
(1) (2)
Kabir Nagar, Durgakund, Varanasi-05, Ph. (0542) – 2314896
The major product of the following reaction is:
in the presence of NaOH
followed by acidification produces compound X as the major product. X on treatment with (CH3CO)2O in the
produces:
(3)
Sol. Ans. (3)
77. An aqueous solution contains an unknown concentration of Ba2+. When 50 mL of a 1M solution Na2SO4 is added, BaSO4 just beings to final volume is 500 mL. The solubility product of BaSO4 is 1 10—10. What is the original concentrationof Ba2+: (1) 1.1 10—9 M (3) 5 10—9
Sol. Ans. (1)
78. Which of the following compounds will be suitable for
Kjeldahl’s method for nitrogen estimation:
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(4)
An aqueous solution contains an unknown
. When 50 mL of a 1M solution just beings to precipitate. The
final volume is 500 mL. The solubility product of . What is the original concentration
(2) 1.0 10—10M (4) 2 10—9 M
Which of the following compounds will be suitable for Kjeldahl’s method for nitrogen estimation:
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(1) (2) (3) (4)
Sol. Ans. (4)
79. When metal ‘M’ is treated with NaOH, a white
gelatinous precipitate ‘X’ is obtained, which is soluble in excess of NaOH. Compound ‘X’ when heated strongly gives an oxide which is used in chromatography as an adsorbent. The metal ‘M’ is:(1) Al (2) Fe (3) Zn (4) Ca
Sol. Ans. (1)
80. An aqueous solution contains 0.10 M H
HCl. If the equilibrium constants for the formation of HS from H2S is 1.0 10—7 and that of
ions is 1.2 10—23 then the concentration of
aqueous solution is:
(1) 6 10—21 (2) 5 10—
(3) 5 10—8 (4) 3 10—
Sol. Ans. (4)
Kabir Nagar, Durgakund, Varanasi-05, Ph. (0542) – 2314896
treated with NaOH, a white
gelatinous precipitate ‘X’ is obtained, which is soluble in excess of NaOH. Compound ‘X’ when heated strongly gives an oxide which is used in chromatography as an adsorbent. The metal ‘M’ is:
An aqueous solution contains 0.10 M H2S and 0.20 M
HCl. If the equilibrium constants for the formation of
and that of 2S from HS
entration of 2S ions in
—19 —20
81. The recommended concentration of fluoride ion in
drinking water is up to 1ppm as fluoride ion is required
to make teeth enamel harder by converting
])OH(Ca.)PO(Ca3[ 2243 to:
(1) ]CaF.)PO(Ca3[ 2243
(3) ]CaF[ 2
Sol. Ans. (1)
82. The compound that does not produce nitrogen gas by
the thermal decomposition is:
(1) NH4NO2
(3) Ba(N3)2
Sol. Ans. (2)
83. The predominant form of histamine present in human
blood in (pKa, Histidine = 6.0) (1) (3)
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The recommended concentration of fluoride ion in
drinking water is up to 1ppm as fluoride ion is required
to make teeth enamel harder by converting
(2) ]CaF].)OH(Ca(3[ 22
(4) ])OH(Ca).CaF(3[ 22
The compound that does not produce nitrogen gas by
the thermal decomposition is:
(2) (NH4)2SO4
(4) (NH4)2Cr2O7
The predominant form of histamine present in human , Histidine = 6.0)
(2)
(4)
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Sol. Ans. (2)
84. The oxidation state of Cr in [
266 )HC(Cr[ and ()CN(Cr[K 22
respectively are: (1) +3, 0, and +6 (2) +3, 0 and +4(4) +3, +4 and +6 (4) +3, +2 and +4
Sol. Ans. (1)
85. Which types of ‘defect’ has the presence of cations in
the interstitial sites: (1) Frenkel defect (2) Metal deficiency defect(3) Schottky defect (4) Vacancy defect
Sol. Ans. (1)
Kabir Nagar, Durgakund, Varanasi-05, Ph. (0542) – 2314896
,Cl])OH(Cr[ 362
)NH)(O()O( 322
(2) +3, 0 and +4 +2 and +4
Which types of ‘defect’ has the presence of cations in
(2) Metal deficiency defect (4) Vacancy defect
86. The combustion of benzene (I) gives COH2O(l). Given that heat of combustion of benzene at constant volume is –3263.9 kJ molcombustion (in kJ mol—1) of benzene at constant pressure will be (R = 8.314 JK(1) 3260 (3) 4152.6
Sol. Ans. (2)
87. Which of the following are Lewis acids:
(1) PH3 and SiCl4 (3) PH3 and BCl3
Sol. (2)
88. Which of the following compounds contain(s) no
covalent bond(s): KCl, PH3, O2, B2H6, H2SO4 (1) KCl (3) KCl, B2H6, PH3
Sol. Ans. (1)
89. For 1 molal aqueous solution of the following
compounds, which one will show the highest freezing point: (1) OH2.Cl]Cl)OH(Co[ 2242
(2) OH3].Cl)OH(Co[ 2332
(3) 362 Cl])OH(Co[
(4) OH.Cl]Cl)OH(Co[ 2252
Sol. Ans. (2)
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The combustion of benzene (I) gives CO2(g) and O(l). Given that heat of combustion of benzene at
3263.9 kJ mol—1 at 25ºC, heat of ) of benzene at constant
pressure will be (R = 8.314 JK—1 mol—1) : (2) –3267.6
(4) –452.46
Which of the following are Lewis acids:
(2) BCl3 and AlCl3 (4) AlCl3 and SiCl4
of the following compounds contain(s) no
(2) KCl, B2H6 (4) KCl, H2SO4
For 1 molal aqueous solution of the following compounds, which one will show the highest freezing
O
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90. According to molecular orbital theory, which of the
following will not be a viable molecule:
(1) 2H (2) 2
2H
(3) 22He (4)
2He
Sol. Ans. (2)
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According to molecular orbital theory, which of the following will not be a viable molecule:
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