Grand Test 5
Grand Test 5
l
A) d l B) d C) d l D) d l
4 2 2
3. Figure shows a short magnet executing small oscillations in a uniform magnetic field
directed into page and magnitude 24 T. The period of oscillation is 0.1 s. When the
key K is closed, an upward current of 18A is established as shown. The new time period
is_____(Neglect the effect of earth’s magnetic field)
A) The kinetic energy of satellite increases and the gravitational potential energy of
satellite – earth system increases.
B) The kinetic energy of satellite increases and the gravitational potential energy of
satellite – earth system decreases.
C) The kinetic energy of satellite decreases and the gravitational potential energy of
satellite – earth system decreases.
D) The kinetic energy of satellite decreases and the gravitational potential energy of
satellite – earth system increases.
Where a and b are constant. What is the effective value of adiabatic constant ?
A) a B) b 1 C) a 1 D) b
b b a a
6. The root mean square speed of the molecules of a diatomic gas is v. when the
temperature is doubled, the molecules dissociate into two atoms. The new root mean
square speed of the individual atom is
A) 2v B) v C) 2v D) 4v
7. In young’s double slit experiment, the two slits are coherent sources of equal amplitude
and wave length . In another experiment with the same setup, two slits are sources of
equal amplitude ‘A’and wavelength , but are incoherent. The ratio of intensities of light
at the midpoint of the screen in the first case to that in second case, is
A) 2 : 1 B) 1 : 2 C) 3 : 4 D) 4 : 3
i) I = I1 + I2 ii) I = I1 + I3
iii) I = I2 + I4 iv) I = I1 + I2 + I3 + I4
A) (i) and (iii) B) (ii), (iii) and (iv) C) Only (ii) D) Only (iv)
10. A cylindrical container filled with a liquid is being rotated about its central axis at a
constant angular velocity . Four points A, B, C and D are chosen in the same plane
such that ABCD is a square of side length a and AB is horizontal while BC is vertical.
A and D lie on the axis of rotation. Let the pressure at A, B, C and D be denoted by
PA, PB, PC and PD respectively. Now, consider the following two statements.
2g
(i) PC> PA for all values of (ii) PB> PD only if
a
A) Both (i) and (ii) are correct B) (i) is correct and (ii) is incorrect
C) (ii) is correct and (i) is incorrect D) Both (i) and (ii) are incorrect
Two point dipoles p k and p k are located at (0, 0, 0) and (1 m 0, 2m) respectively. The
^ ^
11.
2
resultant electric field due to the two dipole at the point (1m, 0, 0) is…
9p ^ 7p ^ 7p ^ 11 p
A) k B) k C) k D)
32 0 32 0 32 0 32 0
13. A metallic rod of length ' l ' is tied an insulating string of length 2l and made to rotate
with angular speed on a horizontal table with one end of the string fixed. If there is a
vertical magnetic field ‘B’ in the region, the e.m.f. induced across the ends of the rod is:
1
A) 2 B) 10 C) D) 5
2
18. A point charge q is placed at a distance r from the center of a thin metallic neutral
spherical shell of radius R as shown in fig. electric potential at point A is
1 q 1 q 1 q q 1 1
A) B) C) D)
4 0 R 4 0 r 4 0 2
R r 2 4 0 r R
19. There is a plot of binding energy per nucleon Eb, against the nuclear mass M; A, B, C, D,
E, F correspond to different nuclei.
A) (i) and (iii) B) (ii) and (iv) C) (ii) and (iii) D) (i) and (iv)
20. An R-L-C series circuit with 100 resistance is connected to an AC source of 200 V
and = 300 rad/s. When only capacitor is removed, the current lags behind voltage by
600. When only inductor is removed, the current leads voltage by 600. The power
dissipated in the R-L-C circuit is
SECTION-II
(NUMERICAL VALUE ANSWER TYPE)
This section contains 10 questions. The answer to each question is a Numerical value. If the Answer in the
decimals , Mark nearest Integer only. Have to Answer any 5 only out of 10 questions and question will be
evaluated according to the following marking scheme:
Marking scheme: +4 for correct answer, -1 in all other cases.
21. A 15 kg block is initially moving along a smooth horizontal surface with a speed of
v 4 m / s to the left. It is acted by a force F, which varies in the manner shown.
If the velocity of the block at t = 15 seconds is ‘X’. Then the value of X =__
Given that, F 40cos t
10
22. A convex lens of focal length f = 20 cm is cut into two equal pieces and the pieces are
separated by 3mm as shown in the figure. A point object O is placed at a distance of 30
cm. The distance between the two image points formed will be (in mm)
23. A ball of mass m moving horizontally with a velocity strikes the bob of a pendulum at
rest. The mass of the bob is also m. If the collision is perfectly inelastic, the height to
v2
which the system will rise is given by h , then the value of x is
x.g
24. A copper wire is held at the two ends by rigid supports. At 300 C, the wire is just taut,
with negligible tension. Find the speed of transverse waves (in m/s) in this wire at 100 C
in decimeter/second [Given, for copper: Young’s modulus = 1.3 x 1011 N/m2, coefficient
of linear expansion = 1.7 x 10-5C-1, density = 9 x 103 kg/m3.]
25. In a meter bridge, the wire of length 1 m has a non - uniform cross section such that, the
dR
variation of its resistance R with length l is dR 1 . Two equal resistances are
dl dl l
connected as shown in the figure. The galvanometer has zero deflection when the jockey
is at point P. The length AP is X (in m), then 100X = …
26. The forward – bias voltage of a diode is changed from 0.6 V to 0.7 V, the current
changes from 5 mA to 15 mA. What is the value (in ) of the forward bias resistance?
27. The binding energy of an electron in the ground state of the He atom is equal to
E0 24.6eV . Find the energy required (in eV) to remove both electrons from the He atom.
28. In the circuit shown in the adjoining figure, the reading of ideal ammeter A (in ampere)
is:
5
29. A solid spherical ball of radius m is connected to a point A on the wall with the help
9
of a string which makes an angle 450 with the vertical. The sphere can rotate freely
about its central axis and it is set into rotational motion against the vertical face of the
wall with an angular velocity 100 rad s-1. In how much time (in s) will it come to rest?
0.1& g 10 m / s 2
30. A resonance tube is old and has jagged end. It is still used in the laboratory to
determine velocity of sound in air. A tuning fork of frequency 512 Hz produces first
resonance when the tube is filled with water to a mark 11cm below a reference mark,
near the open end of the tube. The experiment is repeated with another fork of
frequency 256 Hz which produces first resonance when water reaches a mark 27 cm
below the reference mark. The velocity of sound in air (in m/s), obtained in the
experiment, is close to_____
CHEMISTRY MAX.MARKS: 100
SECTION – I
(SINGLE CORRECT ANSWER TYPE)
This section contains 20 multiple choice questions. Each question has 4 options (1), (2), (3) and (4) for its answer,
out of which ONLY ONE option can be correct.
Marking scheme: +4 for correct answer, 0 if not attempted and -1 if not correct.
31. In which of the following pairs, the hybridization of central atom is same, but shape is
not the same?
33. 22.44 kJ of energy is required to convert 8 g of gaseous metal, M to M+(g). If the first
ionisation energy of the metal is 374 kJ/mol, select the incorrect statement from the
following.
34. Assertion(A):The single N–N bond is weaker than the single P–P bond
Reason(R):High inter electronic repulsion of the non–bonding electrons due to the small
N–N bond length
In the light of the above statements, choose the correct answer from the options given
below:
A) Both (A) and (R) true but (R) is not the correct explanation of (A)
C) Both (A) and (R) true and (R) is correct explanation of (A).
38. The NH3 evolved from 0.5 gm of the organic compound in KJeldhal’s estimation of
Nitrogen neutralizes 10 ml of 1M H2 SO 4 . Identify the incorrect statement out of the
following.
A) Percentage of nitrogen in the organic compound is 56%
B) 20 milli moles of NH3 is produced
C) 10 milli moles of NH3 is produced
D) if the evolved NH3 were neutralized by 10 ml of 1M HCl, the % of nitrogen, would
have been 28%.
39.
CH3
CH3
A) B) C) D)
Br Br Br Br Br
40. O NH
O
O
(I) (II) (III) (IV) (V)
Ease of SN1 reactions among these compounds upon treatment with aqueous NaOH will
be in the order as:
A) (I) > (II) > (III) > (IV) > (V) B) (IV) > (I) > (III) > (II) > (V)
C) (I) > (IV) > (III) > (II) > (V) D) (V) > (IV) > (III) > (II) > (I)
41.
A
i BH /THF
3
ii H O / OH
2 2
B
B
HF
C
The compound(C) is
A) B)
C) D)
42. When neopentyl alcohol is heated with an acid, it slowly converted into an 85 : 15
mixture of alkenes A and B, respectively. Then, the ratio between number of hyper
conjugated structures for A and B is :
A) 5 : 9 B) 5 : 1 C) 1 : 5 D) 9 : 5
43. End product in the following sequence of reactions is :
A) B) C) D)
44.
A) B)
C) D)
45. Given below are two statements, one is labelled as Assertion (A) and other is labelled
as Reason(R):
Assertion (A): Gabriel phthalimide synthesis cannot be used to prepare aromatic
primary amines.
Reason (R): Aryl halides do not undergo nucleophilic substitution reaction at room
temperature.
In the light of the above statements, choose the correct answer from the options given
below:
A) Both (A) and (R) true but (R) is not the correct explanation of (A)
A) 1101 mol L1 B) 1102 mol L1 C) 1103 mol L1 D) 1.9 105 mol L1
48. 50 g of antifreeze (ethylene glycol) is added to 200 g water. What amount of ice will
separate out at 9.30 C ? K f 1.86 K kg mol 1 .
A) 38.71 mg B) 42 g C) 38.71 g D) 42 mg
49. An energy of 24.6eV is required to remove the first electron from helium atom. The
energy required to remove both electrons from helium atom is
50. For the first order reaction 3 A B concentration varies with time as shown in the
adjacent graph. The half – life of the reaction would be
54. How many of the following groups activates benzene ring towards electrophilic aromatic
substitution?
O
||
NHCOR, OCOR, C O R, NR 2 , NH 2 , OH, OR
55. .
The number of iodoform molecules produced per molecule of the reactant in above
reaction is ______
56. How many of the following are more reactive than acetaldehyde towards nucleophilic
addition?
FCH2CHO, O2N CH2CHO , CH3CH2CHO, CH3COCH3, PhCHO, PhCOCH3
57. At what pH the oxidation potential of hydrogen electrode will be 0.413 V?
2.303RT
0.059V (Given: PH 2 1 atm )
F
58. If E Ag
0
/ Ag
0.8V ; K sp AgCl 10 10 M 2 and ECl0 / AgCl / Ag is ‘x’ volts, then the value of 10x is:
2.303RT
0.06V
F
59. A buffer is 0.25 M in CH 3 COOH and 0.56 M in CH 3 COONa . What is the value of pH if
0.006 mol of HCl is added to 0.300 L of a buffer solution?
pK a CH3COOH 4.7 log10 2 0.3
0
60. NH 4 HS S is added to a closed vessel containing H 2 S g at 1 atm and 27 C. If the total
pressure at equilibrium is 3 atm at 270C, then, the value of K P [in (atm)2] is :
MATHEMATICS MAX.MARKS: 100
SECTION – I
(SINGLE CORRECT ANSWER TYPE)
This section contains 20 multiple choice questions. Each question has 4 options (1), (2), (3) and (4) for its answer,
out of which ONLY ONE option can be correct.
Marking scheme: +4 for correct answer, 0 if not attempted and -1 if not correct.
61. If ‘ ’ is a complex number satisfying the relation 1 3(1 i) . Then equals to
1 1
A) 3i B) 3i
4 4
1
C) 3i D) No such complex number exists
4
62. The greatest integral value of k such that both the roots of the equation
k 5 x 2 2kx (k 4) 0 are positive, one root is less than 2 and the other root lies
between 2 and 3 is
A) 13 B) 14 C) 23 D) 24
3 1
63. Let matrix A then I A (where I is a unit matrix of order 2) equals to
99
6 2
64. In a bag there are three tickets with number 1, 2, 3. A ticket is drawn at random and the
number is noted and put back in the bag, this is repeated for four times. Then the chance
that the sum of those numbers is even is
39 40 41 42
A) B) C) D)
81 81 81 81
d
65. If g ( y ) y 5 2 y 3 3 y 4, then the value of 28
dy
g 1 ( y ) at y 2 is
1
A) 2 B) 1 C) D) 2
14
x 4 y 5 z 1 x 2 y 1 z
66. Given lines ,
2 4 3 1 3 2
S1: The lines are intersecting
S2: The lines are not parallel
A) Both S1 and S2 are true B) S1 is true and S2 are false
C) S1 is false and S2 is true D) Both S1 and S2 are false
cos
67. . sin d
cos
1 1
A) B) C) 2 D) 4
2 4
dy tan y
69. The solution of the differential equation (1 t ) et sec y is, where ‘ c ’ is an
dt (1 t )
arbitrary constant
A) cos y et c t 1 B) cos y et c x 1
C) sin y et c t 1 D) sin y et c t 1
A) 1 B) 2 C) 3 D) 4
71. If 3 6 2 then the maximum value of the independent term of x in the expansion of
x x 1/6 0, 0 is
1/3 9
A) 42 B) 68 C) 84 D) 148
1
A) {1} B) {1, 2} C) {1, 2} D) , 1
2
73. The mean and variance of the marks obtained by the students in a test are 10 and 4
respectively. It is known that one of the students got ‘12’ instead of 8. If the new mean
of the marks is 10.2 then the new variance is equal to
C) lim
/ 2
f ( ) does not exist
D) lim
/ 2
f ( ) 1
cos r o
79. The sum of possible integral values of k for which the point P(0, k) lies on or inside the
triangle formed by the lines y 3x 2 0, 3 y 2 x 5 0 and 4 y x 14 0 is
A) 4 B) 5 C) 6 D) 7
x 1 y 1 z x 1 y 3 z 1
80. The acute angle between the lines and where a b c
a b c b c a
and a, b, c are the roots of the equation t 3 t 2 4t 4 0 is
63 4 2 3
A) sin 1 B) cos 1 C) tan 1 D) cos 1
9 9 3 13
SECTION-II
(NUMERICAL VALUE ANSWER TYPE)
This section contains 10 questions. The answer to each question is a Numerical value. If the Answer in the
decimals , Mark nearest Integer only. Have to Answer any 5 only out of 10 questions and question will be
evaluated according to the following marking scheme:
Marking scheme: +4 for correct answer, -1 in all other cases.
81. If ( p iq) 2018 p iq . Then the number of real ordered pairs ( p, q) that satisfy the given
N
equation is N. Then where [ x] represents G.I.F. equals to _________
100
82. An equilateral triangle has its centroid at the origin and one side is x y 1 , then the sum
of the slopes of the other two sides is
84. If x1 , x2 are the roots of x 2 x K 0 and x3 , x4 are the roots of x 2 4 x L 0 such that
x1 , x2 , x3 , x4 are in G.P. Then the product of the integral values of K and L is ______
t t2 1 t3
85. The total number of distinct real values of ‘t’ for which 2t 4t 2 1 8t 3 10 is _____
3t 9t 2 1 27t 3
86. If
dt 1
2 log 1 1 f (t ) c then 3 lim f (t ) _________
t
2
t (1 t ) t t
87. Let A 1, 2, 3, 4, 5 . The number of unordered pairs of subsets P and Q of A such that
P Q is ‘n’. Then the sum of digits of n is __________
88. If , , is the foot of perpendicular drawn from the point P(1, 0, 3) to the line joining
the points A(4, 7, 1) and B(3, 5, 3) . Then the value of 3 6 9 ______
xy g ( x) . g ( y ) g (3)
89. If g ; x, y R, g (1) g 1 (1) then 1 ________
2 2 g (3)
(1 y )1/ y e1
90. The value of real number ‘k’ for which the right hand limit lim is a non-
y 0 yk
CHEMISTRY
31 D 32 C 33 B 34 C 35 B
36 D 37 C 38 C 39 D 40 B
41 C 42 D 43 B 44 B 45 C
46 C 47 C 48 C 49 B 50 B
51 3 52 8 53 4 54 6 55 1
56 2 57 7 58 2 59 5 60 2
MATHEMATICS
61 D 62 C 63 D 64 C 65 D
66 C 67 C 68 D 69 D 70 B
71 C 72 B 73 C 74 B 75 A
76 C 77 B 78 C 79 B 80 B
81 20 82 4 83 10 84 64 85 2
86 3 87 5 88 46 89 3 90 1
SOLUTIONS
PHYSICS
^ ^
^ ^
1. Initial velocity of stone w.r.t lift 20sin 300 j 20cos300 i 10 3 i 10 j m / s
^ ^
Initial velocity of stone w.r.t ground 10 3 i 12 j m / s
The initial position of stone and lift are same and when they again meet their final positions will also
be same. So both will have same displacement in vertical direction in same time
1 t2
Displacement of lift 2 t 1 t 2 2t
2 2
1
Displacement of stone 12 t 10 t 2 12t 5t 2
2
2
t
So 2t 12t 5t 2
2
2
11t 20
10t or t sec
2 11
20
So time taken by stone to return to the floor of lift is sec
11
dW
2. For W to be maximum; 0;
dx
i.e., F x 0 x l , x 0
Clearly for d l , the work done is maximum.
Alternate Solution:
External force and displacement are in the same direction
work will be positive continuously so it will be maximum when displacement is maximum.
I 4 107 18
3. B 0 T 18t
2 r 2 0.2
I I
Now, T 2 and T 2 d
MBH M BH B
T BH T 24
Dividing or 2
T BH B T 24 18
T 2 0.1s 0.2 s
4. In the circular motion around the earth, the centripetal force on the satellite is a gravitational force.
Therefore, v 2 GM / R , where M is the mass of the Earth, R is the radius of the orbit of satellite and
G is the universal gravitational constant. Therefore, the kinetic energy increases with the decrease in
the radius of the orbit. The gravitational potential energy is negative and decreases with the decrease
in radius.
5. For an adiabatic process,
0 = dU + PdU
or d(a+bPV) + PdV=0
dV dP
or b 1 b 0
V P
or (b+1) log V + b log P = constant
V b 1 p b constant
b 1
or PV b
constant
b 1
b
3RT
6. vrms . According to problem T will becomes 2T and M will become M/2 so the value of vrms
M
will increase by 4 2 times i.e., new root mean square velocity will be 2v .
7. When sources are coherent, then I R I1 I 2 2 I1 I 2 cos
At middle point of the screen, 0 then
I R I I 2 II cos 0 4 I
When sources are in coherent, then I R ' I1 I 2 I I 2I
I R 4I
=2
I R' 2I
l
8. T 2 4 2
g
4 2l
g 2
T
g l T
100 100 2 100
g l T
g
y 2x
g
9. Using perpendicular axis theorem I = I1 + I2 and I = I3 + I4 also, I1 = I2 = I3 = I4 hence option 4 is
wrong.
10. We know that
1
PB PA 2 a 2
2
PD PA ga
1 1
PC PD 2 a 2 PA ga 2 a 2
2 2
Therefore,
Pc PA for all the values of and PB PD only
2g
If
a
^
11. For p k it is equatorial point
1 P ^
E1 k
4 0 1
P^
For k it is axial point
2
P ^
2 k
1 2 1 p k^
E2
4 0 2 3
4 0 8
7p ^
E E1 E2 k
32 0
mv
12. Radius of circular orbit R
qB
2mKE 2mT
qB qB
2
If T becomes double & ‘B” becomes tripled then radius becomes R
9
13. de B x dx
3L
e B x dx
2L
5 B L2
2
14. I d 1mA 103 A
C 2 F 2 106 F
d dV
I D I C CV V
dt dt
dV I D 103
Therefore, 500 Vs 1
dt C 2 106
Therefore, applying a varying potential difference of 500 Vs-1 would produce a displacement current
of desired value.
15. Radius of circular path described by a charged particle in a magnetic field is given
2mK q 2 B 2 r 2 e eB 2 r 2
by r ; Where K = Kinetic energy of electron K
qB 2m m 2
2
1 1
105 1 8 10 20 J 0.5eV
2
1.7 1011 1.6 10 19
2 17
12375
By using W0 E K max eV 0.5eV 4.5eV
2475
16.
1. As mutual repulsive force between the particles is internal for the system and as there is no other
external force on the system, linear momentum of the system is conserved in any direction.
2. As the forces on the particles due to one on the other are equal in magnitude. Opposite in direction
and act along the line joining them always, net torque on the system due to these forces about any
point in space in zero. Therefore angular momentum of the system remains constant about any point
in space.
3. As center of mass of the system lies on the line joining the particles always and force on any of
them is passing through C.M always, torque due to this force on any particle about C.M is zero.
Hence angular momentum of any particle about C.M is conserved individually.
4. About any other point except C.M, torque on any individual particle is not zero. Hence angular
momenta of individual particles change but total angular momentum of the system remains constant.
17.
1
2 l l0 2 l
l
2 l 22 l
4 l 2
1
l 0.25m
4
26. The forward biased resistance of a diode is
V 0.7 06
R
I 15 5 103
01
R 10
10 10 3
27. Energy required to remove first electron is 24.6 eV. After removing first electrons from this atom, it
will become He+
E1 13.6 2
2
as EZ 2
and Z 2
= - 54.4 eV
Energy required to remove this second electrons will be 54.4 eV.
Total energy required to remove both electrons
= 24.6 + 54.4
= 79 eV
1 12
28. Req = 0.3 0.3 1.5
1 1 1 10
2 4 12
Applying ohm’s law,
V IR
1.5
I 1A
1.5
29. FBD of the spherical ball
CHEMISTRY
2
31. A) SO3 & CO3 ; Both are sp & planar triangular
40. Reactivity order IV > I > III > II > V on the basis of R and I effect of associated groups.
41.
CH2 CH=CH2 Friedal- craft's aklylation
A=
C=
42.
43. Cleavage of the double bond by Ozonolysis, iodoform Rxn, dry distillation of calcium salts to give
cyclopentanone, followed by wolf–kishner reduction to give cyclohexane.
44. Benzyllic oxidation to give potassium salt of Benzoic acid, followed by acidification to give Benzoic
acid.
45. Gabriel pthalamide synthesis
I1 24.6eV
I 2 I H Z 2 13.6 22 54.4eV
E 24.6 54.4 79 eV
50. 3A B
t 4 min; a 3 x x
a
4x a x
4
At 4 min 75% of first order is completed.
2t1 t
t75% 1 2 min .
2 2
51. X 12 Mg ; Y 15 P
52. conceptual
53. Greater the stability of carbanion, greater is the rate of decarboxylation.
Except CH 3 3 C COOH remaining are more reactive than CH 3COOH .
O
||
54. Except C O R , remaining are ring activating groups.
55.
K P 2 1 2 atm 2 .
MATHS
2 2
61. Clearly ( x 1) y ( x 3) i ( y 3)
y 3 and ( x 1) 2 9 ( x 3) 2
1
x
4
1
But 3i does not satisfy the given equation
4
2k k 4
62. Let f ( x) x 2 x 0 by the given data, f (0) 0, f (2) 0, f (3) 0
k 5 k 5
k 4
0 ………. (1)
(k 5)
k 24
0 …….. (2)
(k 5)
4k 49
0 …….. (3)
(k 5)
49
From (1), (2) and (3), k , 24
4
2
63. Here A A A is an Idempotent matrix
A A2 A3 .......... A99
Hence ( I A)99 I 299 1 A
64. We can take 3 cases namely four odd numbers, two odd numbers and zero odd numbers.
Let X be the number of odd numbers chosen
P(sum is even) P ( X 4) P ( X 2) P ( X 0)
4 2 2 4
2 2 1 1 41
4 C2
3 3 3 3 81
65. Let f ( y ) be the inverse of g ( y )
f ' g ( y ) g '( y ) 1
1 1
f ' g (2) g '(2) 1 g 1 y
y 2 f ' 1 14
66. S1 and S2 are skew lines
cos x x sin x
67. I dx
x.cos x
Put x.cos x t 2 I 2 x.cos x c
x2 d x2
0 k x d
d 0 k x
d
68. I lim lim
0 sin 0 (1 cos )
(By. L. Hospitals Rule)
2
k 2
lim 2 1 k 4
0 2sin / 2
k
69. Given equation can be reduced to
dy 1
cos y sin y et (1 t )
dt 1 t
dy dv
Put sin y v cos y
dt dt
sin y
Hence the solution is et c
(t 1)
cot k y tan k y 2 cot 1 k 0 has real roots
1 2 1 3/ 2 2
70.
D 0 tan 1 k / 3 k 3 and sum of roots 0, product of roots 0
k 0 and k 3
71. Let Tr 1 be the Independent term of x then r 6,
t61 84 3 6
72. Check for what values of x , g '( x) 0 or does not exist
2
73. Mean
x i
10 and Variance
x 2
i xi
4
n n n
x 2
i
104
x i
4
102
n n n
n 20
Hence new Variance = 3.96
1
2
74. From the graph of the functions, the required area = 2
x x 2 dx
3
0
x3 7 x 2 11x 2 f max 3
Clearly 1 is the root a + b + c + = 0
x x x
1 2 n
.... 1
n 1 n 1 n 1
0
1
78. Clearly k cot 22 2 1
2
Hence 100 (k 1) 141
79. Use L11 . L22 0 for three sides of the triangle
80. Clearly a 2; b 1 and c 2 and
81. p 2 q 2 1 or p 2 q 2 0
1
z 2018 z z 2019 1
z
So there are total 2020 solutions
82. The inclination of the line L x y 1 is 1350 . So the slopes of the other two sides will be
tan 1350 600
83. E a b 2c. a c . b
a b 2 c . a c .b a .b
2 2
But a c . b c 0
a .c b . c a .b 1
E 8 2 10
84. Let the common ratio of G.P. be ‘ r ’ then x2 x1r , x3 x1r 2 , x4 x1r 3
And x1 x2 1, x1 x2 K , x3 x4 4, x3 . x4 L
r 2 and x1 1
K 2, L 32
t t2 1 t3
85. 2t 4t 2 1 8t 3 10
3t 9t 2 1 27t 3
1 1 1 1 1 1
3 6
x 2 4 1 x 2 4 8 10
1 9 1 3 9 27
6 x 6 x3 5 0 x 3 5 / 6 or x3 1
dt
86. I 2
dt
1
t 2 1 1
t
1
Put 1 U
t
1 2
Then I 2 log 1 1 c
t 1
1 1
t
2
f (t )
1
1 1
t
35 1
87. The number of un-ordered pairs of subsets of A is 122
2
88. If ‘Q’ is the foot of perpendicular and it divide AB in the ratio :1 then
3 4 5 7 3 1
Q , ,
1 1 1
Now PQ perpendicular AB 7 / 4
5 7 17
, , , ,
3 3 3
3 6 9 46
g (2 x) g ( x)
89. Using the derivative from the first principle g 1 ( x) g (1)
2x x
g 1 ( x) 1
g ( x) x
n (1 y )