# JEE Mains 2014 Solved Paper with detailed Answers

This year’s JEE (Joint Entrance Exam) Mains exam test was held on 6th April 2014. Tens of lakh student’s were attended this exam to get admission in IITs and AIEEE colleges. Students search for fully solved paper, questions and detailed solution is going to end now. This JEE question Paper 1 contains 90 questions from Maths, Physics and Chemistry subject streams.

CareerVendor brings full solution of each & every question of JEE 2014 exam. Have a look at the below questions and their detailed solution with answer.

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## IIT JEE Main 2014 paper solution with answers:

Here are questions from all three paper categories, i.e. Chemistry, Physics and Mathematics. Have a look at the solution provided with reasons. For a reference we are taking Test Booklet Code H in account.

[divider]

PART – A: PHYSICS

[divider]

1.  The pressure that has to be applied to the ends of a steel wire of length 10 cm to keep its length constant when its temperature is raised by 100°C is :

(For steel Young’s modulus is 2×1011 N m–2 and coefficient of thermal expansion is 1.1×10–5 K–1)
(1)  2.2 × 107 Pa                                             (2)  2.2 × 106 Pa
(3)  2.2 × 108 Pa                                             (4)  2.2 × 109 Pa

Sol.  3

0.10 × 1.1 × (10)³–5 × 100 = ( F/A  * 0.10) / 2*10

2 ´1011

\    F = Pressure = 1.1 × 10–5 × 100 × 2 × 1011

A

= 2.2 × 108 Pa

2.           A conductor lies along the z-axis at –1.5 £ z < 1.5 m and carries a fixed current of 10.0 A in – aˆ z direction (see

1.5

 y

figure). For a field B = 3.0 ´10-4 e-0.2 x  aˆ
T, find the                                                                    I

power required to move the conductor at constant speed to x = 2.0 m, y = 0 m in 5 × 10-3 s. Assume parallel motion along the x-axis

(1)  14.85 W                                                   (2)  29.7 W (3)  1.57 W                                                     (4)  2.97 W

2.0 xy

B– 1.5

Sol.       4

Work Done

ò Fdx

ò IbB.dx

P =                     =            =

Time              t                t

2

ò  (10)(3)(3´ 104 e0.2 x  )dx

=  0

5 ´10-3

 2

9 ´10-3  é e-0.2 x  ù

 ë        û

= 5 ´10-3  ê – 0.2 ú

= 9 éë1 – e-0.4

= 2.97 W

0

Ques 3.  A bob of mass m attached to an inextensible string of length     is suspended from a vertical support. The bob rotates in a horizontal circle with an angular speed  w  rad/s about the vertical. About the point of suspension :

(1)  angular momentum changes in direction but not in magnitude. (2)  angular momentum changes both in direction and magnitude. (3)  angular momentum is conserved.

(4)  angular momentum changes in magnitude but not in direction.

Sol.       1

                                                                                                                                                                                          

L changes in direction not in magnitude                                      L

Ä V

Ques 4.  The current voltage relation of diode is given by I = (e1000V/T – 1) mA, where the applied voltage V is in volts and the temperature T is in degree Kelvin. If a student makes an error measuring  ± 0.01 V while measuring the current of 5 mA at 300 K, what will be the error in the value of current in mA ?

(1)  0.5 mA                                                     (2)  0.05 mA (3)  0.2 mA                                                     (4)  0.02 mA

Sol.       (3)

1000 V 5 = e

T  – 1

= 6

…(1)

 Þ   e 1000   V T

1000 V

Again, I = e
T  – 1

 T

dI  = e
1000 V  1000

dV                T

1000

T

1000 V

e T      dV

Using (1)

DI = 1000 ´ 6 ´ 0.01 = 60 =  60  = 0.2mA

T                      T     300

Ques 5. An open glass tube is immersed in mercury in such a way that a length of 8 cm extends above the mercury level. The open end of the tube is then closed and sealed and the tube is raised vertically up by additional 46 cm. What will be length of the air column above mercury in the tube now? (Atmospheric pressure = 76 cm of Hg)

(1)  38 cm                                                       (2)  6 cm

(3)  16 cm                                                       (4)  22 cm

Sol.       (3)

(76) (8) = (54 – x) (76 – x)

x = 38 cm

Length of air column = 54 – 38 = 16 cm

air        8
46 + 8 = 54 air       8

air

x

Ques 6. Match List-I (Electromagnetic wave type) with List-II (Its association / application) and select the correct option from the choices given below the lists:

 List – I List – II (a) Infrared waves (i) To treat muscular strain (b) Radio waves (ii) For broadcasting (c) X-rays (iii) To detect fracture of bones (d) Ultraviolet rays (iv) Absorbed by the ozone layer of the atmosphere

 (a) (b) (c) (d) (1) (iii) (ii) (i) (iv) (2) (i) (ii) (iii) (iv) (3) (iv) (iii) (ii) (i) (4) (i) (ii) (iv) (iii) Sol. 2

Infrared waves ® To treat muscular strain radio waves ® for broadcastingX-rays ® To detect fracture of bones

Ultraviolet rays ® Absorbed by the ozone layer of the atmosphere;

Ques 7. A parallel plate capacitor is made of two circular plates separated by a distance of 5 mm and with a dielectric of dielectric constant 2.2 between them. When the electric field in the dielectric is 3 × 104 V/m, the charge density of the positive plate will be close to :

(1)  3 × 104 C/m2                                                                    (2)  6 × 104 C/m2

(3)  6 × 10–7 C/m2                                                                  (4)  3 × 10–7 C/m2

Sol.       3

By formula of electric field between the plates of a capacitor E =   s

Ke0

Þ s = EKe0

= 3 ´104

´ 2.2 ´ 8.85 ´10

-12

= 6.6 ´ 8.85 ´10-8

= 5.841´10-7

@ 6 ´10-7   C/m2

Ques 8. A student measured the length of a rod and wrote it as 3.50 cm. Which instrument did he use to measure it? (1)  A screw gauge having 100 divisions in the circular scale and pitch as 1 mm.

(2)  A screw gauge having 50 divisions in the circular scale and pitch as 1 mm. (3)  A meter scale.

(4)  A vernier calliper where the 10 divisions in vernier scale matches with 9 division in main scale and main scale has 10 divisions in 1 cm.

Sol.       4

Least count of vernier calliper is  1  mm = 0.1 mm = 0.01 cm

Ques 9.  Four particles, each of mass M and equidistant from each other, move along a circle of radius R under the action of their mutual gravitational attraction. The speed of each particle is :

(1)      GM (1+ 2  2 ) R
(2)   1   GM (1+ 2  2 )

2     R

(3)      GM R

(4)

2  2  GM R

Sol.       2

Net force on any one particle                                                                     M

u

GM2

=           +

(2R ) 2

GM2

(R   2 ) 2

cos 45° +

GM 2

(R   2 ) 2

cos 45°                         u

GM 2  é 1    1 ù

 ê
 ú

=               +

 2

R 2     ë 4         û

45°

M                                            M

45°

This force will be equal to centripetal force so

Mu 2

GM2  é1 + 2  2 ù                                                                                        u

=          ê            ú

 M

R         R 2     ë     4     û                                                          uu =    GM é1 + 2  2 ù =  1   GM (2  2 +1)

4R ë            û     2     R

Ques 10.  In a large building, there are 15 bulbs of 40 W, 5 bulbs of 100 W, 5 fans of 80 W and 1 heater of 1kW. The voltage of the electric mains is 220 V. The minimum capacity of the main fuse of the building will be :

(1)  12 A                                                         (2)  14 A (3)  8 A                                                           (4)  10 A

Sol.       1

Item                 No.                   Power

40 W bulb        15                     600 Watt

100 W bulb      5                       500 Watt

80 W fan          5                       400 Watt

1000 W heater 1                       1000 Watt

Total Wattage = 2500 Watt

So current capacity i =  P =  2500 = 125 = 11.36 @ 12 Amp.

V     220      11

Ques 11. A particle moves with simple harmonic motion in a straight line. In first t s, after starting from rest it travels a distance a, and in next t s it travels 2a, in same direction, then :

(1)  amplitude of motion is 4a                                      (2) time period of oscillations is 6t

(3)  amplitude of motion is 3a                                      (4) time period of oscillations is 8t

Sol.        2

A(1 – cos wt) = a

A( 1 –  cos 2wt) = 3a

cos wt = æ1 –  a ö

ç     A ÷

è         ø

cos 2wt = æ1 – 3a ö

ç      A ÷

 2

2 æ1 –  a ö
è          ø

– 1 = 1 – 3a

ç     A ÷                A

è         ø

Solving the equation

a  =  1

A    2

A = 2a

cos wt = 1

2

T = 6t

 Sol. (1) 3A (2) 6A (3) 30 mA1 m0 H = m0 ni (4) 60 mA 3 ´103  = 100 ´ i Þ i = 3A0.1

Ques 12. The coercivity of a small magnet where the ferromagnet gets demagnetized is 3 ´ 103 Am-1. The current required to be passed in a solenoid of length 10 cm and number of turns 100, so that the magnet gets demagnetized when inside the solenoid, is:

Ques 13.  The forward biased diode connection is:

(1)       2V                             4V                          (2)       -2V                           +2V

(3)      +2V                           -2V                         (4)       -3V                           -3V

Sol.        3

By diagram

Ques 14. During the propagation of electromagnetic waves in a medium:

(1)  Electric energy density is equal to the magnetic energy density. (2)  Both electric and magnetic energy densities are zero.

(3)  Electric energy density is double of the magnetic energy density. (4)  Electric energy density is half of the magnetic energy density.

Sol.        1

Ques 15. In the circuit shown here, the point ‘C’ is kept connected to point

‘A’ till the current flowing through the circuit becomes constant. Afterward, suddenly, point ‘C’ is disconnected from point ‘A’ and connected to point ‘B’ at time t = 0. Ratio of the voltage across resistance and the inductor at t = L/R will be equal to :

(1) -1                                                                            (2) 1 – e e

A       C      R B

L

(3)     e

1 – e

(4) 1

Sol.        4

Since resistance and inductor are in parallel, so ratio will be 1.

Ques 16.  A mass ‘m’ is supported by a massless string wound around a uniform hollow cylinder of mass m and radius R. If the string does not slip on the cylinder, with what acceleration will the mass fall on release?

 R

Sol.        4

For the mass m,

mg – T = ma

for the cylinder,

TR = mR 2  a

R

Þ   T = ma

Þ   mg = 2ma

Þ   a = g/2

Ques 17. One mole of diatomic ideal gas undergoes a cyclic process ABC as shown in figure. The process BC is adiabatic. The temperatures at A, B and C are 400 K, 800 K and 600 K respectively. Choose the correct

P statement:  (1) The change in internal energy in the process AB is -350 R.  (2) The change in internal energy in the process BC is -500 R.  (3) The change in internal energy in whole cyclic process is 250 R.  (4) The change in internal energy in the process CA is 700 R.

Sol.2

 (1) 2gH = nu2(n -2) (2) gH = (n -2)u2 Sol. (3) 2gH = n2u21 Time to reach the maximum height (4) gH = (n -2)2u2

Ques 18.  From a tower of height H, a particle is thrown vertically upwards with a speed u. The time taken by the particle, to hit the ground, is n times that taken by it to reach the highest point of its path.  The relation between H, u and n is:

t  =  u

1       g

If t2 be the time taken to hit the ground

-H = ut
– 1 gt 2

2        2    2

But t2 = nt1 (given)

nu    1   n 2 u 2

Þ   -H = u      –   g

g     2     g2

Þ   2gH = nu2(n – 2)

Ques 19.  A thin convex lens made from crown glass æ m =  3 ö has focal length f. When it is measured in two different

ç       2 ÷

liquids having refractive indices  4

3

relation between the focal lengths is:

è         ø

 1

and  5 , it has the focal lengths f3

and f2

respectively. The correct

(1) f2 > f and f1 becomes negative                                (2) f1 and f2 both become negative

(3)  f1 = f2 < f                                                                (4) f1 > f and f2 becomes negative

Sol.        4

m   =   (m1)

f      æ m

ç m

ö

– 1÷

è   m           ø

 – 1

æ 3     öç        ÷

Þ    f1   =   è 2     ø   = 4

f     æ 3 / 2 – 1ö

ç 4 / 3     ÷

è            ø

Þ   f1 = 4f

 – 1

æ 3     ö

 f            2

ç        ÷

2   =   è          ø   = -5

f     æ 3 / 2 – 1ö

ç 5 / 3     ÷

è            ø

Þ   f2 < 0

Ques 20. Three rods of Copper, Brass and Steel are welded together to from a Y –shaped structure. Area of cross – section of each rod = 4 cm2. End of copper rod is maintained at 100°C where as ends of brass and steel are kept at 0°C. Lengths of the copper, brass and steel rods are 46, 13 and 12 cms respectively. The rods are thermally insulated from surroundings except at ends. Thermal conductivities of copper, brass and steel are

0.92, 0.26 and 0.12 CGS units respectively. Rate of heat flow through copper rod is : (1) 4.8 cal/s                                                                   (2) 6.0 cal/s

(3) 1.2 cal/s                                                                   (4) 2.4 cal/s

Sol.        1

dQ1   = dQ2   + dQ3

dt        dt       dt

 +

Þ           0.92(100 – T) = 0.26(T – 0)0.12(T   0-)

dQ/dt

100°C

1

46

Þ          T = 40°C

13                 12                                      k1

dQ1  =  0.92 ´ 4(100 – 40) = 4.8 cal/s

dt                  40

k2                             k3

2       dQ2/dt            3

dQ3/dt

0°C                          0°C

Ques 21.   A pipe of length 85 cm is closed from one end.   Find the number of possible natural oscillations of air column in the pipe whose frequencies lie below 1250 Hz. The velocity of sound in air is 340 m/s.

(1) 6                                                                              (2) 4 (3) 12                                                                            (4) 8

Sol.        1

In fundamental mode

l = 0.85

4

l = 4 ´ 0.85

f = v/l =     340

4 ´ 0.85

= 100 Hz.

 = 0.85=l/4

\  Possible frequencies = 100 Hz, 300 Hz, 500 hz, 700 Hz, 900 Hz 1100 Hz below 1250 Hz.

Ques 22.  There is a circular tube in a vertical plane. Two liquids which do not mix and of densities d1 and d2 are filled in the tube. Each liquid subtends 900 angle at centre. Radius joining their interface makes an angle a with vertical. ratio d1/d2 is

(1) 1 + tan a

1 – tan a

(3) 1 + sin a

1 – sin a

(B) 1 + sin a                                                             d2

1 – cos a                                       a

(D) 1 + cos a

1 – cos a

d1

Sol.        1

PA = PB

P0 + d1gR(cos a – sin a) = P0 + d2gR(cosa + sina)

Þ  d1   =  cos a + sin a = 1 + tan a

d2         cos a – sin a

1 – tan a

23.         A green light is incident from the water to the air – water interface at the critical angle (q).   Select the correct statement

(1)  The spectrum of visible light whose frequency is more than that of green light will come out to the air medium.

(2)  The entire spectrum of visible light will come out of the water at various angles to the normal. (3)  The entire spectrum of visible light will come out of the water at an angle of 900 to the normal.

(4)  The spectrum of visible light whose frequency is less than that of green light will come out to the air

medium.

Sol.        4

As frequency of visible light increases refractive index increases.   With the increase of refractive index

critical angle decreases.  So that light having frequency greater than green will get total internal reflection and the light having frequency less than green will pass to air.

24.         Hydrogen (1H1), Deuterium (1H2), singly ionised Helium (2He4)+ and doubly ionised lithium (3Li6)++ all have one electron around the nucleus. Consider an electron transition from n = 2 to n = 1.  If the wave lengths of emitted radiation are l1, l2, l3  and l4  respectively then approximately which one of the following is correct?

(1) l1 = l2 = 4l3 = 9l4                                                                            (2) l1 = 2l2 = 3l3 = 4l4

(3) 4l1 = 2l2 = 2l3 = l4                                                                         (4) l1 = 2l2 = 2l3 = l4

Sol.        1

1 = Rz2 æ  1 –  1  ö

l           ç 12

22  ÷

è            ø

\    l  =     4

3Rz2

l1 =

l2 =

l3 =

l4   =

4

3R

4

3R

4

12R

4

27R

Þ   l1 = l2 = 4l3 = 9l4

25.         The radiation corresponding to 3 ® 2 transition of hydrogen atom falls on a metal surface to produce photoelectrons. These electrons are made to enter a magnetic field of 3 ´ 10-4T.  If the radius of the largest circular path followed by these electrons is 10.0 mm, the work function of the metal is close to :

(1) 0.8 eV                                                                      (2) 1.6 eV (3) 1.8 eV                                                                     (4) 1.1 eV

Sol.        4

mv = qBR

KE(max) =

(mv) 2

2m

= 0.8eV

 4    9
 ê         ú

hn = 13.6 é 1 – 1 ùë         û

\   W = hn – KE.(max)

= 13.6  5  – 0.8 = 1.1eV

36

Ques 26.  A block of mass m is placed on a surface with a vertical cross section given by y = x3/6.  If the coefficient of friction is 0.5, the maximum height above the ground at which the block can be placed without slipping is :

(1) 1 m

3

(3) 1 m

6

(2) 1 m

2

(4)  2 m

3

Sol.        3

mg sin q = mmg cosq

tan q = m

dy = tan q = m =  1 dx                       2

 2

x   = 1 ,  x = ± 1

2     2

y = 1 m .

6

27.         When a rubber-band is stretched by a distance x, it exerts a restoring force of magnitude F = ax + bx2 where a and b are constants. The work done in stretching the unstretched rubber band by L is :

aL2

bL3

+                                                                       (2)

1 æ aL2

ç

bL3  ö

+       ÷

2       3                                                                        2 è

2       3  ø

(3) aL2 + bL3                                                                                                    (4)  1 ( aL2 + bL3)

2

Sol.        1

F = ax + bx2

dw = Fdx

L

W = ò (ax + bx 2 )dx

0

aL2

W =

bL3

+

2       3

28.         On heating water, bubbles being formed at the bottom of the vessel detach and rise.  Take the bubbles to be spheres of radius R and making a circular contact of radius r with the bottom of the vessel.  If r < < R, and the surface tension of water is T, value of r just before bubbles detach is : (density of water is rw)

(1) R 2

(3) R 2

Sol.        None

rw g

T

rw g

3T

(2) R 2

(4) R 2

3rw g

T                                           R

rw g

6T

2r

 q

(2pr T)sin q =

4 pR 3r .g

3         w

T ´  r  ´ 2pr =  4 pR 3r  g

R             3         w

4

r2 =

2  R rw g

3     T

r = R2       2rw g

3T

29.         Two beams, A and B, of plane polarized light with mutually perpendicular planes of polarization are seen through a polaroid. From the position when the beam A has maximum intensity (and beam B has zero intensity), a rotation of Polaroid through 300  makes the two beams appear equally bright.   If the initial intensities of the two beams are IA and IB respectively, then IA/IB equals :

(1) 1                                                                              (2) 1/3

(3) 3                                                                              (4) 3/2

Sol.        2

IA cos230 = IB cos260

IA   =  1

IB         3

30.         Assume that an electric field E = 30x 2 ˆi exists in space.  Then the potential difference VA – VO, where VO is

the potential at the origin and VA the potential at x = 2 m is : (1) -80 J                                                                       (2) 80 J

(3) 120 J                                                                        (4) – 120 J

Sol.        None

E = 30x 2 ˆi

dV = – -ò E.dx

vA                               2

ò dV = -ò 30x 2 dx

v0                                0

VA – V0 = – 80 Volt

[divider] PART – B: MATHEMATICS [divider]

Ques 31. The image of the line

x  1 =  y – 3 = z – 4

in the plane 2x – y + z + 3 = 0 is the line

(1)

3         1         -5

x + 3 =  y – 5 = z – 2

(2)

x + 3 =  y – 5 = z + 2

3          1         -5

-3        -1         5

(3)

x – 3 =  y + 5 = z – 2

(4)

x – 3 =  y + 5 = z – 2

3          1         -5

Sol.        1

-3        -1         5

Line is parallel to plane

Image of (1, 3, 4) is (- 3, 5, 2).

32.         If the coefficients of x3 and x4 in the expansion of (1 + ax + bx2) (1 – 2x)18 in powers of x are both zero, then

(a, b) is equal to

(1) æ16 ,  251 ö

(2) æ14 ,  251 ö

ç         3  ÷

ç         3  ÷

è             ø

(3) æ14 ,  272 ö

è             ø

(4) æ16 ,  272 ö

ç         3  ÷

ç         3  ÷

è             ø                                                                     è             ø

Sol.        4

1(1 – 2x)18 + ax(1 – 2x)18 + bx2(1 – 2x)18

Coefficient of x3 : (–2)3 18C3 + a(–2)2 18C2 + b(–2) 18C1 = 0

4 ´ (17 ´16 )

(3 ´ 2 )

– 2a × 17 + b = 0

2

….. (i)

Coefficient of x4 : (–2)4 18C4 + a(–2)3 18C3 + b(–2)2 18C2 = 0

( 4 ´ 20 ) – 2a × 16 + b = 0

3

….. (ii)

From equation (i) and (ii), we get

4 æ 17 ´ 8 – 20 ö + 2a æ 16 – 17 ö = 0

ç    3            ÷        ç 3      2 ÷

è                  ø        è             ø

æ 17 ´ 8 – 60 ö

2a ( -19 )

4 ç                  ÷ +                 = 0

è        3        ø          6

a =  4 ´ 76 ´ 6

3 ´ 2 ´19

Þ a = 16

Þ b =  2 ´16 ´16 – 80 =  272

3                      3

 (1) (-1, 0) È (0, 1) (3) (-2, -1) (2) (1, 2) (4) (-¥, -2) È (2, ¥) Sol. 1 a2 = 3t2 – 2t For non-integral solution0 < a2 < 1 a Î (- 1, 0) È (0, 1).

33.         If a Î R and the equation -3(x – [x])2 + 2 (x – [x]) + a2 = 0 (where [x] denotes the greatest integer £ x) has no integral solution, then all possible values of a lie in the interval

1

[Note:   It is assumed that a real solution of given equation exists.]                             (0, 0)                   (2/3,0)

            

                                         2

 ë                           û       ë        û

34.         If éa ´ b  b ´ c  c ´ a ù = l éa b c ù
, then l is equal to

(1) 2                                                                              (2) 3 (3) 0                                                                              (4) 1

Sol.        4

                                                 2

 ë                             û    ë        û

éa ´ b   b ´ c   c ´ a ù = éa b c ù

l = 1.

35.         The variance of first 50 even natural numbers is

(1) 833

4

(2) 833

(3) 437                                                                          (4)  437

4

Sol.        2

s2  = ç å x ÷ – x 2

æ        2 ö

è    n    ø

50

å 2r

x =  r =1       = 51

50

50

å 4r 2

s2  =  r =1          – (51)2 = 833

50

36.         A bird is sitting on the top of a vertical pole 20 m high and its elevation from a point O on the ground is

45°. It flies off horizontally straight away from the point O. After one second, the elevation of the bird from

O is reduced to 30°. Then the speed (in m/s) of the bird is

(1) 40 (

2 – 1)

(2) 40 (   3 –   2 )

(3) 20  2                                                                       (4) 20 (

Sol.        4

tan 30º =    20    =   1

20 + x       3

20 + x = 20  3

3 – 1)

20m = h

20m

x = 20 (

3 -1)

p/4    p/6

Þ Speed is 20 (

3 -1) m/sec.

0           20m                  x

p

37.         The integral ò

0

1 + 4 sin 2  x – 4 sin x

2           2

dx equals

(1) p – 4                                                                        (2)  2p – 4 – 4  3

3

(3) 4  3 – 4

Sol.        4

(4) 4  3 – 4 –  p

3

p

I = ò

0

1 + 4 sin 2 x – 4 sin  x dx

2            2

y = 2 sin x/2

2

p

1

 x

= ò 1 – 2 sin 2  dx

0

p / 3

=

æ1 – 2 sin  x ö dx +

p

æ 2 sin  x – 1ö dx                                                                     p                p

ò è                ø

ò è                ø

ç             2 ÷            ç        2     ÷

0                                           p/3                                                                                                                                      3

= æ x + 4 cos x ö

p / 3

p

+ æ -4 cos x – x ö

ç                 ÷         ç                    ÷

è               2 ø 0         è

2      ø p / 3

= – p + 8 ×   3 – 4

3         2

= 4  3 – 4 –  p

3

Ques 38. The statement ~(p « ~q) is

(1) equivalent to p « q                                                (2) equivalent to ~p « q

(3) a tautology                                                              (4) a fallacy

Sol.        1

 P q ~ q p « ~ q ~ (p « ~ q) p « q T T F F T T T F T T F F F T F T F F F F T F T T

39.         If A is an 3 ´ 3 non-singular matrix such that AA¢ = A¢A and B = A-1A¢, then BB¢ equals

 (1) I + B (3) B-1 (2) I(4) (B-1)¢ Sol. 2B = A-1A¢ Þ AB = A¢ ABB¢ = A¢B¢ = (BA)¢ = (A-1A¢A)¢ = (A-1AA¢)¢ = A. Þ BB¢ = I.

40.         The integral

1

æ1 + x – 1 ö x x dx is equal to

ò è           x ø

ç              ÷

x 1

x 1

(1) ( x – 1) e

(3) ( x + 1) e

Sol.        2

x  + c                                                        (2) x e

x 1

x  c                                                        (4) – x e

æ x + 1 ö

x  + c

x 1

+ c

1 + x –  1   eç

x ÷ dx

æ              ö  è         ø

ò ç           x ÷

è              ø

æ x + 1 ö

1     æ x + 1 ö

=    eè

x ø dx +

x æ1 –

ö eè

x ø dx

ç         ÷                                                     ç         ÷

ò           ò  ç          ÷

è     x 2  ø

 x +                             x +                      x +

æ      1 ö                     æ      1 ö              æ      1 öç         ÷                     ç         ÷              ç         ÷

= ò eè

x ø dx + xeè

x ø  – ò eè

x ø dx

 x +

æ      1 öç         ÷

= xeè

x ø  + c

41.         If z is a complex number such that |z| ³ 2, then the minimum value of

z 1

2

(1) is equal to  5

2

(3) is strictly greater than  5

(2) lies in the interval (1, 2)

(4) is strictly greater than  3 but less than  5

Sol.        2

|z| ³ 2

z +  1 ³

z – 1

2                                                                                    2                       2

³  2 – 1 ³  3 .

2             2             2     2

Hence, minimum distance between z and æ – 1 , 0 ö is  3

ç   2     ÷

è           ø      2

42.         If g is the inverse of a function f and f ¢(x) =    1    , then g¢(x) is equal to

1 + x5

(1) 1 + x5                                                                                                             (2) 5x4

(3)          1

1 + {( )}5

(4) 1 + {g x )}5

Sol.        4

f (g (x)) = x

f¢ (g (x)) g¢ (x) = 1 g¢ (x) = 1 + (g ( x ))5

3        1 + f (1)1

+(f2)

43.         If a, b ¹ 0, and f (n) = an + bn and

equal to

1 + f (1)1

1 + f (2)1

+(f2)1      (+3) f

+(3f )1      (+4) f

= K(1 – a)2 (1 – b)2 (a – b)2, then K is

(1) ab                                                                            (2)    1

ab

(3) 1                                                                              (4) -1

Sol.        3

3            1 + a + b

1 + a2 + b2

1 + a + b

1 + a2 + b2

1    1      1

1 + a2 + b2

1 + a3 + b3

1   1     1

1 + a3 + b3

1 + a4 + b4

1       0          0    2

= 1    a     b

1   a   a2    = 1

a – 1

b – 1

1   a2

b2     1

b    b2

1   a2 – 1

b2 – 1

= ((a – 1)(b2 – 1) – (b – 1)(a2 – 1))2

= (a – 1)2(b – 1)2(a – b)2 Þ k = 1

 K                   (                       )                                                  4               6

44.         Let f (x) =  1  sin k  x + cosk x   where x Î R and k ³ 1. Then f (x) – f (x) equalsk

(1) 1

6

(3) 1

4

(2) 1

3

(4)  1

12

Sol.        4

1 (sin 4  x + cos4  x ) – 1 (sin 6  x + cos6  x )

4                               6

3 (sin 4  x + cos4  x ) – 2 (sin 6  x + cos6  x )

=

12

3 (1 – 2 sin 2  x cos2  x ) – 2 (1 – 3 sin 2  x cos2  x )

=

12

=  1  .

12

Ques 45.  Let a and b be the roots of equation px2 + qx + r = 0, p ¹ 0. If p, q, r are in A.P. and  1 +  1

a    b

= 4, then the

value of |a – b| is

(1)   61

9

(3)   34

9

(2)  2  17

9

(4)  2  13

9

Sol.        4

1 + 1 = 4

a    b

2q = p + r

Þ – 2 (a + b) = 1 + ab

Þ – 2 æ  1 +  1 ö =  1  + 1

 a    b

ç          ÷è          ø    ab

Þ  1   = – 9

ab

Equation having roots a, b is 9×2 + 4x – 1 = 0

a, b =

-4 ±   16 + 36

2 ´ 9

|a – b| =  2  13 .

9

 (          )

46.         Let A and B be two events such that P  A È B  =  1 , P Ç ) =  1

6                       4

complement of the event A. Then the events A and B are

and P A ) =  1 , where A stands for the

4

 (1) mutually exclusive and independent (2) equally likely but not independent Sol. (3) independent but not equally likely3 (4) independent and equally likely

 6

P (A È B) =  1

P (A È B) = 5 ,   P (A) =  3

6                    4

P (A È B) = P (A) + P (B) – P (A Ç B) = 5

6

P (B) = 5 –  3 +  1 =  1 .

6    4    4    3

P (A Ç B) = P (A) × P (B)

1 =  3 ´ 1 .

4    4   3

 (1) 2f ¢(c) = g¢(c) (3) f ¢(c) = g¢(c) (2) 2f ¢(c) = 3g¢(c) (4) f ¢(c) = 2g¢(c) Sol. 4Let h(f) = f(x) – 2g(x) as h(0) = h(1) = 2 Hence, using Rolle’s theorem h¢(c) = 0 Þ f¢(c) = 2g¢(c)

47.         If f and g are differentiable functions in [0, 1] satisfying f(0) = 2 = g(1), g(0) = 0 and f(1) = 6, then for some cÎ]0, 1[

48.         Let  the  population  of  rabbits  surviving  at  a  time  t   be  governed  by  the  differential  equation

dp (t )     1

=    p (t ) – 200 . If p(0) = 100, then p(t) equals

dt       2

 (1) 400 – 300 et/2 (2) 300 – 200 e-t/2 Sol. (3) 600 – 500 et/21 (4) 400 – 300 e-t/2

dp =  p 400 dt          2

dp     =  1 dt p – 400    2

ln |p – 400| =  1 t + c

2

at t = 0, p = 100

ln 300 = c

ln  p 400  =  t

300        2

Þ |p – 400| = 300 et/2

Þ 400 – p = 300 et/2 (as p < 400)

Þ p = 400 – 300 et/2

49.         Let C be the circle with centre at (1, 1) and radius = 1. If T is the circle centred at (0, y), passing through origin and touching the circle C externally, then the radius of T is equal to

(1)   3

2

(3) 1

2

(2)   3

2

(4) 1

4

Sol.        4

According to the figure

(1 + y)2 = (1 – y)2 + 1   (y > 0)

Þ y =  1

4

(1, 1)

1 + y

(0, y)

1 – y

1

50.         The area of the region described by A = {(x, y) : x2 + y2 £ 1 and y2 £ 1 – x} is

(1)

(3)

Sol.        1

p +  4

2    3

p –  2

2    3

1           1

(2) (4)

p –  4

2    3

p +  2

2    3

 2

A =    ´ p + 2ò

0

1 – xdx

p/4      2/3

=  p +  4 .

2    3

p/4

2/3

51.         Let a, b, c and d be non-zero numbers. If the point of intersection of the lines 4ax + 2ay + c = 0 and 5bx +

 (1) 2bc – 3ad = 0 (2) 2bc + 3ad = 0 Sol. (3) 3bc – 2ad = 03 Let point of intersection is (h, –h) (4) 3bc + 2ad = 0

2by + d = 0 lies in the fourth quadrant and is equidistant from the two axes then

ì4ah – 2ah + c = 0

Þ í

î5bh – 2bh + d = 0

So,  –   c   = –  d

2a        3b

52.         Let PS be the median of the triangle with vertices P(2, 2), Q(6, -1) and R(7, 3). The equation of the line passing through (1, -1) and parallel to PS is

(1) 4x – 7y – 11 = 0                                                      (2) 2x + 9y + 7 = 0 (3) 4x + 7y + 3 = 0                                                        (4) 2x – 9y – 11 = 0

Sol.        2

S æ 13 , 1ö , P(2, 2)

ç 2      ÷

è          ø

Slope = –  2

9

Equation will be  y + 1 = – 2 x – 1       9

9y + 9 + 2x – 2 = 0

2x + 9y + 7 = 0

sin (p cos2 )

53.

lim

x®0             x2

is equal to(1)

p                                                                             (2) 1

2

(3) -p                                                                            (4) p

Sol.        4

lim

x ®0

sin (p cos2  x )

x 2

sin (p – p sin 2  x )

= lim

x ®0

= lim

x 2

sin (p sin 2  x )

´

p sin 2  x

= p.

x ®0

p sin 2  x            x 2

54.         If X = {4n – 3n – 1 : n Î N} and Y = {9(n – 1) : n Î N}, where N is the set of natural numbers, then XÈY

is equal to

(1) N                                                                             (2) Y – X (3) X                                                                             (4) Y

Sol.        4

Set X contains elements of the form

4n – 3n – 1 = (1 + 3)n – 3n – 1

= 3n + nCn – 13n – 1 ….. nC232

= 9(3n – 2 + nCn – 13n – 1 … + nC2)

Set X has natural numbers which are multiples of 9 (not all)

Set Y has all multiples of 9

X È Y = Y

55.         The locus of the foot of perpendicular drawn from the centre of the ellipse x2 + 3y2 = 6 on any tangent to it is

(1) (x2 – y2)2 = 6x2 + 2y2                                                                         (2) (x2 – y2)2 = 6x2 – 2y2

(3) (x2 + y2)2 = 6x2 + 2y2                                                                         (4) (x2 + y2)2 = 6x2 – 2y2

Sol.        3

Let the foot of perpendicular be P(h, k)

Equation of tangent with slope m passing P(h, k) is

y = mx ±

6m2  + 2 ,  where m = – h k

6h 2

Þ

k 2

+ 2 =

h 2  + k 2

k

6h2 + 2k2 = (h2 + k2)2

So required locus is 6×2 + 2y2 = (x2 + y2)2.

56.         Three positive numbers from an increasing G.P. If the middle term in this G.P. is doubled, the new numbers are in A.P. Then the common ratio of the G.P. is

(1)    2 +   3

(3) 2 –   3

Sol.        4

(2) 3 +   2

(4) 2 +   3

Let numbers be   a, ar, ar2

Now, 2 (2ar) = a + ar2            [a ¹ 0]

Þ 4r = 1 + r2

Þ r2 – 4r + 1 = 0

Þ r = 2 ±    3

r = 2 +   3

(Positive value)

57.         If (10)9 + 2(11)1 (10)8 + 3(11)2 (10)7 + ….. + 10(11)9 = k(10)9, then k is equal to

(1) 121

10

(2)  441

100

(3) 100                                                                          (4) 110

Sol.        3

S = 109 + 2 × 111 × 108 + … + 10 × 119

11 × S =         111 × 108 + … + 9 × 119 + 1110

10

Þ –  1  S = 109  + 111 ×108  + 112 ×107  + … + 119  – 1110

10

 ö

æ æ 11 10           ö- 1

ç ç     ÷        ÷

Þ –  1  S = 109  ç è 10 ø        ÷ – 1110 Þ –  1  S = 1110  – 1010  – 1110

10            ç

ç

11 – 1   ÷                    10

10         ÷

è                 ø

S = 1011

S = 100 × 109

Þ k = 100.

58.         The angle between the lines whose direction cosines satisfy the equations l + m + n = 0 and l2 = m2 + n2 is

Sol.        1

p                                                                             (2)  p

3                                                                                    4

p                                                                             (4)  p

6                                                                                    2

l = – m – n

m2 + n2 = (m + n)2

Þ mn = 0

So possibilities are æ –  1  ,

1  , 0

or æ –  1  , 0,

1  ö

ç      2       2      ÷       ç                       ÷

Þ cos q = 1

2

è                       ø       è

2           2 ø

Þ q =  p .

3

59.         The slope of the line touching both the parabolas y2 = 4x and x2 = -32y is

(1) 1

2

(3) 1

8

(2)  3

2

(4)  2

3

Sol.        1

Equation of tangent at A (t2, 2t)

yt = x + t2 is tangent to x2 + 32y = 0 at B

Þ x2 + 32 æ x + t ö = 0

y2 = 4x

ç t      ÷

è        ø

Þ x2 + 32 x + 32t = 0 t

 2

Þ æ 32 ö  – 4 (32t ) = 0
A(t2, 2t)

B

ç  t  ÷

è     ø

Þ 32 æ 32 – 4t ö = 0

ç t 2               ÷

è            ø

Þ t3 = 8 Þ t = 2.

Þ Slope of tangent is 1 =  1 .

t     2
x2 = -32y

60.         If x = -1 and x = 2 are extreme points of f(x) = alog |x| + bx2 + x, then

(1) a = -6, b = 1

2

(3) a = 2, b = – 1

2

(2) a = -6, b = – 1

2

(4) a = 2, b = 1

2

Sol.        3

f¢(x) =

a + 2bx + 1 x

2bx2 + x + a = 0 has roots –1 and 2

[divider] PART – C: CHEMISTRY [divider]

Ques 61.  Which one of the following properties is not shown by NO? (1)  It combines with oxygen to form nitrogen dioxide

(2)  It’s bond order is 2.5

(3)  It is diamagnetic in gaseous state

(4)  It is a neutral oxide

Sol.        3

NO is paramagnetic in gaseous state due to the presence of unpaired electron in its structure.

62.         If Z is a compressibility factor, van der Waals equation at low pressure can be written as:

(1)

(3)

Sol.        4

æ

ç P +

Z = 1 – Pb                                                   (2)

RT

Z = 1 + RT                                                  (4)

Pb

n 2a ö

2  ÷ ( V – nb ) = nRT

Z = 1 +

Z = 1 –

Pb

RT

a

VRT

è       V   ø

æ        a  ö

For 1 mole, ç P +

è

2 ÷ (V – b) = RT V  ø

PV = RT + Pb –  a +  ab

V    V2

ab

at low pressure, terms Pb &

V2

So, PV = RT –  a

V

Z = 1 –    a     RTV

will be negligible as compared to RT.

63.         The metal that cannot be obtained by electrolysis of an aqueous solution of its salts is: (1)  Cu                                                                          (2)  Cr

(3)  Ag                                                                          (4)  Ca

Sol.        4

During the electrolysis of aqueous solution of s-block elements, H2 gas is obtained at cathode.

64.         Resistance of 0.2 M solution of an electrolyte is 50 W. The specific conductance of the solution is 1.4 S m-1.

The resistance of 0.5 M solution of the same electrolyte is 280 W. The molar conductivity of 0.5 M solution of the electrolyte in S m2 mol-1 is:

(1)  5 × 103                                                                                                       (2)  5 × 102

(3)  5 × 10-4                                                                                                      (4)  5 × 10-3

Sol.        3

50 =  1 ´

K   A

50 =  1  ´

1.4   A

= 70 m–1

A

280 =  1 ´ 70

K

K =  1 S m–1

4

L   =  1 ´ æ 1000 ö (10-2 m)3

m       4   ç  M  ÷

è         ø

=  1 ´ 1000 ´10-6

4     0.5

= 500 ´10-6  = 5 ´10-4 Sm2 mol–1

65.         CsCl crystallises in body centred cubic lattice. If ‘a’ is its edge length then which of the following expressions is correct?

3

(1)

r  +   + r –   =      a

(2)

r  +   + r –   =   3a

Cs            Cl             2

Cs          Cl

3a

(3)

r  +   + r

–   = 3a

(4)

r  +   + r  –   =

Sol.        1

Cs            Cl

Cs           Cl            2

In CsCl structure, Cs+ ion is in contact with Cl– ion at the nearest distance which is equal to    3 a

2

Cl

• ·

Cs+

• ·

Cl

• ·

66.         Consider separate solutions of 0.500 M C2H5OH(aq), 0.100 M Mg3(PO4)2(aq), 0.250 M KBr(aq) and 0.125

M Na3PO4(aq) at 25oC. Which statement is true about these solutions, assuming all salts to be strong electrolytes?

(1)  0.125 M Na3PO4(aq) has the highest osmotic pressure. (2)  0.500 M C2H5OH(aq) has the highest osmotic pressure. (3)  They all have the same osmotic pressure.

(4)  0.100 M Mg3(PO4)2(aq) has the highest osmotic pressure.

Sol.        3

For C2H5OH, p = 1 ´ 0.5 ´ RT For KBr, p = 2 ´ 0.25 ´ RT

For Mg3(PO4)2, p = 5 ´ 0.1 ´ RT For Na3PO4, p = 4´ 0.125 ´ RT So, all are isotonic solutions.

67.         In which of the following reactions H2O2 acts as a reducing agent?

 2

+              –

(a)

H 2 O2  + 2H

+ 2e

¾¾® 2H 2 O

(b) (c)

H 2 O2  – 2e

H 2 O2  + 2e

–  ¾¾® O  + 2H +

–  ¾¾® 2OH –

–              –

(d)

H 2 O2  + 2OH

– 2e

¾¾® O2  + 2H 2 O

 (1)  (a), (c) (2)  (b), (d) Sol. (3)  (a), (b)2 (4)  (c), (d)

A reducing agent loses electrons during redox reaction.

Hence (b, d) is correct.

68.         In SN2 reactions, the correct order of reactivity for the following compounds: CH3Cl, CH3CH2Cl, (CH3)2CHCl and (CH3)3CCl is:

(1)  CH3CH2Cl > CH3Cl > (CH3)2CHCl > (CH3)3CCl (2)  (CH3)2CHCl > CH3CH2Cl > CH3Cl > (CH3)3CCl (3)  CH3Cl > (CH3)2CHCl > CH3CH2Cl > (CH3)3CCl (4)  CH3Cl > CH3CH2Cl > (CH3)2CHCl > (CH3)3CCl

Sol.        4

Rate of SN

2 reaction µ                            1

steric over crowding in transition state

 (1)  L3 < L2 < L4 < L1 (2)  L1 < L2 < L4 < L3 Sol. (3)  L4 < L3 < L2 < L14 Strong  field  ligands  cause  higher  magnit (4)  L1 < L3 < L2 < L4 ude  of  crystal  field  splitting

69.         The octahedral complex of a metal ion M3+  with four monodentate ligands L1, L2, L3  and L4  absorb wavelengths in the region of red, green, yellow and blue, respectively. The increasing order of ligand strength of the four ligands is:

 ¾¾¾¾¾¾¾¾

V I B G Y O R ® decrea sin g energy
which  is  accompanied  by  the

70.         For the estimation of nitrogen, 1.4 g of organic compound was digested by Kjeldahl method and the

evolved ammonia was absorbed in 60 mL of  M

10

sulphuric acid. The unreacted acid required 20 ml of   M

10

sodium hydroxide for complete neutralization. The percentage of nitrogen in the compound is: (1)  3%                                                                         (3)  5%

(3)  6%                                                                         (4)  10%

Sol.        4

% of N = 1.4 ´ milliequivalents of acid consumed mass of organic compound

Meq of acid consumed = æ 60 ´  1 ´ 2 ö – æ 20 ´  1 ´  ö

ç        10     ÷   ç

10  1÷

= 10

\=% of  N

 1

=  .  ´  10

1.4

è                  ø   è                 ø

10%

Ques 71.   The equivalent conductance of NaCl at concentration C and at infinite dilution are lC and l¥, respectively.

The correct relationship between lC and l¥ is given as: (where the constant B is positive)

 (1)  lC = l¥ – (B)    C (2)  lC = l¥ + (B)    C Sol. (3)  lC = l¥ + (B)C1 (4)  lC = l¥ – (B)C

According to Debye Huckel’s Theory for a strong electrolyte,

lC  = l¥  – B  C

 2(g )                  2(g )                           3(g )                P           C

72.         For the reaction, SO     +  1 O       SO     , if K  = K  (RT)x

2

the value of x is: (assuming ideality)

where the symbols have usual meaning then

(1)   1

2

(2)  1

(3)  -1                                                                          (4)   – 1

2

Sol.        4

For reaction:

SO     + 1 O       SO

2(g )       2   2(g )                           3(g )

Dn  = – 1 = x

g              2

Ques 73.  In the reaction,

 3

CH COOH ¾L¾iAlH¾4 ® A ¾P¾Cl5¾® B ¾A¾lc.K¾OH¾® C,the product C is:

 (1)  Ethylene (2)  Acetyl chloride Sol. (3)  Acetaldehyde1 (4)  Acetylene

CH3COOH ¾L¾iAlH¾4 ® CH3CH2OH ¾P¾Cl5¾® CH3CH2Cl

alc. KOH

H2C      CH2

(ethylene)

74.         Sodium phenoxide when heated with CO2  under pressure at 125°C yields a product which on acetylation produces C.

ONa

+CO

 ¾¾125¾® B ¾¾¾® C

c                                   H+2        5 Atm                     Ac2 O

The major product C would be: (1)           OH

COOCH3

(2)          OCOCH3

(3)          OCOCH3

COOH

(4)          OH
COOH

COCH3

Sol.        3

ONa¾¾¾CO¾2      ¾®

OH

 +

¾H¾3O¾®
COCH3

OH

¾A¾c2¾O ®

OCOCH3

1250 C, 5 atm

COO- Na +

COOH

(Aspirin)

COOH

 (1)  an alkyl cyanide (2)  an alkyl isocyanide Sol. (3)  an alkanol2 (4)  an alkanediol

Ques 75.   On heating an aliphatic primary amine with chloroform and ethanolic potassium hydroxide, the organic compound formed is:

RNH2 + CHCl3 + 3KOH ¾¾®

RNC ­  + 3KCl + 3H2O

(alc.)                 (alkyl isocyanide )

76.         The correct statement for the molecule, CsI3 is:

(1)  it contains Cs3+ and I- ions.                                   (2)  it contains Cs+, I- and lattice I2 molecule.

(3)  it is a covalent molecule.                                       (4)  it contains Cs+ and I3

Sol.     4
ions.

 3                                    3

CsI
¾¾® Cs+  + I-

Þ Cs cannot show +3 oxidation state.

 4 –

Þ I2 molecules are too large to be accommodated in lattice.

77.         The equation which is balanced and represents the correct product(s) is:

ëéMg ( H2 O )6

ûù    + ( EDTA )

¾e¾xces¾s  Na¾OH¾® éëMg (EDTA )

2+

+ 6H2 O

(2)

CuSO 4  + 4KCN ¾¾® K 2 éëCu (CN )4

+ K 2SO 4

(3)   Li2O + 2KCl ¾¾® 2LiCl + K2O

 2+

+                 +

2+                      +              –

(4)

Sol.        4

éëCoCl ( NH3 )5

+ 5H

¾¾® Co

+ 5NH4  + Cl

Equation – 1 is not balanced w.r.t. charge. Equation – 2 gives K3 [Cu(CN)4] as product.

Equation – 3 reaction is unfavourable in the forward direction (K2O is unstable, while Li2O is stable). Equation – 4 is correct & balanced.

78.         For which of the following molecule significant m ¹ 0?

(a)           Cl

Cl

(c)         OH

OH

(b)         CN

CN

(d)          SH

SH

(1)  Only (c)                                                                 (2)  (c) and (d) (3)  Only (a)                                                                 (4)  (a) and (b)

Sol.        2

H                                   H O                                   S

O                                   S

H                                   H

Due to infinite possible conformations in the above cases (of which only one has zero m); a weighted m will finally exist.

 Initial Concentration (A) Initial Concentration (B) Initial rate of formation of C (mol L-S-) 0.1 M 0.1 M 1.2 ´ 10-3 0.1 M 0.2 M 1.2 ´ 10-3 0.2 M 0.1 M 2.4 ´ 10-3

79.         For the non – stoichiometre reaction 2A + B ¾¾® C + D , the following kinetic data were obtained in three separate experiments, all at 298 K.

The rate law for the formation of C is:

(1)

dc = k [A ][B]2                                                                                                           (2)

dt

dc = k [A]

dt

Sol.        2

dc = k [A ][B]

dt

(4)

dc = k [A ]2 [B]

dt

R = k [A ]x [B]y

1.2 ´ 10-3  = k [0.1]x  [0.1]y

1.2 ´ 10-3  = k [0.1]x  [0.2]y

2.4 ´ 10-3  = k [0.2]x  [0.1]y

Solving x = 1, y = 0

R = k[A]

80.         Which series of reactions correctly represents chemical reactions related to iron and its compound?

(1)

(2)

Fe ¾C¾l2 ,¾hea¾t ® FeCl  ¾h¾eat¾, air¾® FeCl  ¾Z¾n ® Fe

 3    4                   ¾                        ¾

Fe ¾O¾2 ,h¾eat¾® Fe O  ¾C¾O,¾6000 C¾® FeO ¾C¾O,¾7000 C ® Fe

(3)

dil H2SO4

 3                                     2

H2SO4 , O2

(       )      heat

(4)
Fe ¾¾¾¾® FeSO4 ¾¾¾¾¾® Fe2

O2 ,heat                      dil H2SO4

SO4  3 ¾¾¾® Fe

heat

Fe ¾¾¾¾® FeO ¾¾¾¾® FeSO4 ¾¾¾® Fe

Sol.        2

In Eq. (1) FeCl3 cannot be reduced when heated in air.

In Eq. (3) Fe2(SO4)3 cannot convert to Fe on heating; instead oxide(s) will be formed.

In Eq. (4) FeSO4 cannot be converted to Fe on heating; instead oxide(s) will be formed.

Hence Eq. (2) is correct.

Ques 81.   Considering the basic strength of amines in aqueous solution, which one has the smallest pKb value?

(1)   (CH3 )3 N                                                              (2)

(3)   (CH3 )2 NH                                                           (4)

Sol.        3

Aliphatic amines are more basic than aromatic amines.
C6H5 NH2

CH3 NH2

(CH3)2NH > CH3NH2 > (CH3)3N (among aliphatic amines in water).

82.         Which one of the following bases is not present in DNA?

(1)  Cytosine                                                                (2)  Thymine

Sol.        3

Adenine, Thymine, Cytosine, Guanine are bases present in DNA.

Quinoline an aromatic compound is NOT present in DNA.

N

(Quinoline)

83.         The correct set of four quantum numbers for the valence elections of rubidium atom (Z= 37) is:

(1) (3)

5, 1, 1, + 1

2

5, 0 , 0, + 1

2

(2) (4)

5, 0 , 1, + 1

2

5,1, 0, + 1

2

Sol.        3

37

Rb = [Kr] 5 s1

n = 5, l = 0, m = 0, s = + 1

2

84.         The major organic compound formed by the reaction of 1, 1, 1– trichloroethane with silver powder is: (1)  2- Butyne                                                               (2)  2- Butene

(3)  Acetylene                                                              (4)  Ethene

Sol.        1

Cl                                                          Cl

H3C     C           Cl

Cl
+ 6Ag

Cl          C

Cl

CH3

H3C

C          C   CH3

2 – butyne

+ 6AgCl ¯

 85. Given below are the half-cell reactions:Mn2+ + 2e- ¾¾® Mn; E0 = -1.18 V 2 (Mn 3+ + e- ¾¾® Mn 2+ )  ; E0 = +1.51 V The E0 for 3Mn2+ ¾¾® Mn + 2Mn3+   will be: (1)  – 0.33 V; the reaction will not occur (2) – 0.33 V; the reaction will occur (3)  – 2.69 V; the reaction will not occur (4) – 2.69 V; the reaction will occur Sol. 3

Mn +2  + 2e-  ¾¾® Mn  E o  = -1.18 V

2Mn +2  ¾¾® 2Mn +3  + 2e-

3Mn +2  ¾¾® Mn + 2Mn +3

E o  = -1.51 V

E o  = SOP + SRP

= – 1.18 + (- 1.51)

= – 2.69 V

Negative EMF reflects non-spontaneous cell reaction.

86.         The ratio of masses of oxygen and nitrogen in a particular gaseous mixture is 1 : 4. The ratio of number of their molecule is:

(1)  1: 8                                                                         (2)  3 : 16 (3)  1 : 4                                                                        (4)  7 : 32

Sol.        4

w

Moles of O2  =

32

4w

Moles of N2 =

28

 2

n O    =  w ´  28
7

 N

n        32   4w    322

87.         Which one is classified as a condensation polymer?

(1)  Teflon                                                                    (2)  Acrylonitrile

(3)  Dacron                                                                   (4)  Neoprene

Sol.        3

Teflon, Acrylonitrile and Neoprene are addition polymers while Dacron is a condensation polymer.

88.         Among the following oxoacids, the correct decreasing order of acid strength is:

(1) (3)

Sol.        1

HClO4 > HClO3 > HClO2 > HOCl

HOCl > HClO2  > HClO3 > HClO4

(2) (4)

HClO2 > HClO4 > HClO3 > HOCl

HClO4 > HOCl > HClO2 > HClO3

HClO < HClO2 < HClO3 < HClO4

Increasing acid strength due to increase in oxidation state of central atom.

89.         For complete combustion of ethanol, C2H5OH () + 3O2 (g ) ¾¾® 2CO2 (g ) + 3H2O (),  the amount of heat produced as measured in bomb calorimeter, is 1364.47 kJ mol–1 at 250C. Assuming ideality the Enthalpy of combustion, DCH, for the reaction will be: (R = 8.314 kJ mol–1)

(1)  –1460.50 kJ mol–1                                                                            (2)  – 1350.50 kJ mol–1

(3)  – 1366.95 kJ mol–1                                                                           (4)  – 1361.95 kJ mol–1

Sol.        3

C2 H5OH () + 3O2 (g ) ¾¾® 2CO2 (g ) + 3H2O ()

DE = -1364.47 kJ / mole

DH = ?

T = 298 K

Dn g  = -1

 DH = DE + Dn g RT

So, DH = -1366.95 kJ / mole

Ques 90.  The most suitable reagent for the conversion of R – CH2 – OH ¾¾® R – CHO is:

(1)  CrO3                                                                                                             (2)  PCC (Pyridinium Chlorochromate) (3)  KMnO4                                                                                                      (4)  K2Cr2O7

Sol.        2

 PCC

RCH 2 OH ¾¾¾® RCHO