16 + Interview Questions in Jee Mains in Jee Page 1 InterviewSolution

1.	The enthalpies of neutralisation of a strong acid HA and weaker acid HB by NaOH are -13.7 and -12.7 kcal/eq. When one equivalent of NaOH is added to a mixture containing 1 equivalent of HA and HB; the enthalpy change was -13.5kcal. In what ratio is the base distributed between HA and HB?
Answer» Let x equivalent of HA and y equivalent of HB are taken in the mixture x + y = 1 ... (i) x × 13.7 + y × 12.7 = 13.5 … (ii) Solving eqs. (i) and (ii), we get x = 0.8, y = 0.2 x: y = 4: 1

1.

The enthalpies of neutralisation of a strong acid HA and weaker acid HB by NaOH are -13.7 and -12.7 kcal/eq. When one equivalent of NaOH is added to a mixture containing 1 equivalent of HA and HB; the enthalpy change was -13.5kcal. In what ratio is the base distributed between HA and HB?

Answer»

Let x equivalent of HA and y equivalent of HB are taken in the mixture

x + y = 1 ... (i)

x × 13.7 + y × 12.7 = 13.5 … (ii)

Solving eqs. (i) and (ii), we get

x = 0.8, y = 0.2

x: y = 4: 1

Discussion

2.	Curves A and B describe the log P versus log V relation for helium, hydrogen, O3and PH3during adiabatic process. Curve C is for(A) He(B) H2(C) O3(D) PH3
Answer» Explanation (A) He For an adiabatic process = constant or, log P +γlogV = constant log P = -γlog V = constant Thus the slope of log P versus log V graph is -γ. The value ofγis maximum for helium, a monoatomic gas. Thus curve C should correspond to helium.

2.

Curves A and B describe the log P versus log V relation for helium, hydrogen, O3and PH3during adiabatic process. Curve C is for(A) He(B) H2(C) O3(D) PH3

Answer»

Explanation

(A) He

For an adiabatic process

= constant

or, log P +γlogV = constant

log P = -γlog V = constant

Thus the slope of log P versus log V graph is -γ. The value ofγis maximum for helium, a monoatomic gas.

Thus curve C should correspond to helium.

Discussion

3.	The enthalpies of neutralization of HClO4and Cl3C – COOH are –13.5 kcal/g equivalent and –14.7 kcal/g equivalent respectively. When 40 gm of solid NaOH is added to a mixture of 1 gm mol HClO4and 1 g mol Cl3C – COOH, solution perchlorate and sodium trichloroacetate are formed in molar ratio of 3 : 1. Then(A)ΔH for the reaction of NaOH with the mixture is 6.45 kcal(B)ΔH for the reaction of NaOH with the mixture is 13.8 kcal(C) After reaction the total number of moles of acid remained are 0.5 (HClO4and Cl3C – COOH)(D) After reaction the total weight of acid remained is 147.75 gm (HClO4and Cl3C – COOH) andΔH for the reaction of NaOH with mixture is –13.8 kcal.
Answer» Explanation (D) After reaction the total weight of acid remained is 147.75 gm (HClO4and Cl3C – COOH) andΔH for the reaction of NaOH with mixture is –13.8 kcal. Let x mole of NaOH are used in Ist reaction and (1–x) mol ofNaOH are used in 2nd reaction.

3.

The enthalpies of neutralization of HClO4and Cl3C – COOH are –13.5 kcal/g equivalent and –14.7 kcal/g equivalent respectively. When 40 gm of solid NaOH is added to a mixture of 1 gm mol HClO4and 1 g mol Cl3C – COOH, solution perchlorate and sodium trichloroacetate are formed in molar ratio of 3 : 1. Then(A)ΔH for the reaction of NaOH with the mixture is 6.45 kcal(B)ΔH for the reaction of NaOH with the mixture is 13.8 kcal(C) After reaction the total number of moles of acid remained are 0.5 (HClO4and Cl3C – COOH)(D) After reaction the total weight of acid remained is 147.75 gm (HClO4and Cl3C – COOH) andΔH for the reaction of NaOH with mixture is –13.8 kcal.

Answer»

Explanation

(D) After reaction the total weight of acid remained is 147.75 gm (HClO4and Cl3C – COOH) andΔH for the reaction of NaOH with mixture is –13.8 kcal.

Let x mole of NaOH are used in Ist reaction and (1–x) mol ofNaOH are used in 2nd reaction.

Discussion

4.	Time period of a block when suspended from the upper plate of a parallel plate capacitor by a spring of stiffness k,is T,when block is uncharged. If a charge qis given to the block, then the new time period of oscillation will be(a) T(b) > T(c) < T(d)≥ T
Answer» The correct option is(a) T. Explanation: The forces that act on the block are qE. mg and spring force. Since, qE and mg are constant forces, the only variable elastic force changes by k x, where x is elongation in the spring. Unbalanced (restoring) force,

4.

Time period of a block when suspended from the upper plate of a parallel plate capacitor by a spring of stiffness k,is T,when block is uncharged. If a charge qis given to the block, then the new time period of oscillation will be(a) T(b) > T(c) < T(d)≥ T

Answer»

The correct option is(a) T.

Explanation:

The forces that act on the block are qE. mg and spring force. Since, qE and mg are constant forces, the only variable elastic force changes by k x, where x is elongation in the spring.

Unbalanced (restoring) force,

Discussion

5.	A point performs SHM along a straight line with a period T = 0.60 s and amplitude a = 10 cm. Starting from extreme position, in what time, the point travels a distance a/2?(A) 10 s(B) 1.0 s(C) 0.1 s(D) 0.01 s
Answer» The Correct option is (C) 0.1 s

5.

A point performs SHM along a straight line with a period T = 0.60 s and amplitude a = 10 cm. Starting from extreme position, in what time, the point travels a distance a/2?(A) 10 s(B) 1.0 s(C) 0.1 s(D) 0.01 s

Answer»

The Correct option is (C) 0.1 s

Discussion

6.	Which is least reactive towards nucleophilic substitution (SN2)
Answer» Correct option (C) Explanation: Due to the presence of –Cl group which is a +M group.

6.

Which is least reactive towards nucleophilic substitution (SN2)

Answer»

Correct option (C)

Explanation:

Due to the presence of –Cl group which is a +M group.

Discussion

7.	Statement-I : The graph of potential energy and kinetic energy of a particle in SHM with respect to position is a parabola.Statement-II : Potential energy and kinetic energy do not vary linearly with position.(a) If both Statement- I and Statement- II are true, and Statement - II is the correct explanation of Statement– I.(b) If both Statement - I and Statement - II are true but Statement - II is not the correct explanation of Statement – I.(c) If Statement - I is true but Statement - II is false.(d)If Statement - I is false but Statement - II is true.
Answer» (b) If both Statement - I and Statement - II are true but Statement - II is not the correct explanation of Statement – I.

Discussion

8.	Acceleration-displacement graph of a particle executing SHM Is as shown in given figure. The time period of its oscillation is: (in sec)(A)π/2(B) 2π(C) π(D) π/4
Answer» The Correct option is(B) 2π

8.

Acceleration-displacement graph of a particle executing SHM Is as shown in given figure. The time period of its oscillation is: (in sec)(A)π/2(B) 2π(C) π(D) π/4

Answer»

The Correct option is(B) 2π

Discussion

9.	A cylinder of radius R made of a material of thermal conductivity K1 is surrounded by a cylindrical shell of inner radius R and outer radius 2R made of a material of thermal conductivity K2 . The two ends of the combined system are maintained at two different temperatures. There is no loss of heat across the cylindrical surface and the system is in steady state. The effective thermal conductivity is-(A) K1 + K2(B) K1 K2/K1+K2(C) K1+3K2/4(D) 3K1 +K2/4
Answer» Correct option(C) K1+3K2/4 Explanation:

9.

A cylinder of radius R made of a material of thermal conductivity K1 is surrounded by a cylindrical shell of inner radius R and outer radius 2R made of a material of thermal conductivity K2 . The two ends of the combined system are maintained at two different temperatures. There is no loss of heat across the cylindrical surface and the system is in steady state. The effective thermal conductivity is-(A) K1 + K2(B) K1 K2/K1+K2(C) K1+3K2/4(D) 3K1 +K2/4

Answer»

Correct option(C) K1+3K2/4

Explanation:

Discussion

10.	Two rods of same material and thickness are joined as shown below. The ends X and Y are maintained at XºC and YºC respectivelythe ratio of heat flow at M and N are Q1 and Q2 respectively. Then –(A) Q1 = Q2(B) Q1 > Q2(C) Q1 < Q2(D) Q1 = Q2/2
Answer» Correct option(C) Q1 < Q2 Explanation:

10.

Two rods of same material and thickness are joined as shown below. The ends X and Y are maintained at XºC and YºC respectivelythe ratio of heat flow at M and N are Q1 and Q2 respectively. Then –(A) Q1 = Q2(B) Q1 > Q2(C) Q1 < Q2(D) Q1 = Q2/2

Answer»

Correct option(C) Q1 < Q2

Explanation:

Discussion

11.	A whistle emitting a sound of frequency 440Hz is tied to a string of 1.5 m length and rotated with an angular velocity of 20 rad/sec in the horizontal plane. Then the range of frequencies heard by an observer stationed at a large distance from the whistle will be: (v= 330 m/s):(A) 400.0 Hz to 484.0 Hz(B) 403.3 Hz to 480.0 Hz(C) 400.0 Hz to 480.0 Hz(D) 403.3 Hz to 484.0 Hz
Answer» Correct option(D) 403.3 Hz to 484.0 Hz Explanation:

11.

A whistle emitting a sound of frequency 440Hz is tied to a string of 1.5 m length and rotated with an angular velocity of 20 rad/sec in the horizontal plane. Then the range of frequencies heard by an observer stationed at a large distance from the whistle will be: (v= 330 m/s):(A) 400.0 Hz to 484.0 Hz(B) 403.3 Hz to 480.0 Hz(C) 400.0 Hz to 480.0 Hz(D) 403.3 Hz to 484.0 Hz

Answer»

Correct option(D) 403.3 Hz to 484.0 Hz

Explanation:

Discussion

12.	The graph shows the variation of temperature (T) of one kilogram of a material with the heat (H) supplied to it. At O, the substance is in the solid state. From the graph, we can conclude that(A) T2 is the melting point of the solid(B) BC represents the change of state from solid to liquid(C) (H2 – H1) represents the latent heat of fusion of the substance(D) (H3 – H1) represents the latent heat of vaporization of the liquid
Answer» Correct option(C) (H2 – H1 ) represents the latent heat of fusion of the substance Explanation: Length = letent heat

12.

The graph shows the variation of temperature (T) of one kilogram of a material with the heat (H) supplied to it. At O, the substance is in the solid state. From the graph, we can conclude that(A) T2 is the melting point of the solid(B) BC represents the change of state from solid to liquid(C) (H2 – H1) represents the latent heat of fusion of the substance(D) (H3 – H1) represents the latent heat of vaporization of the liquid

Answer»

Correct option(C) (H2 – H1 ) represents the latent heat of fusion of the substance

Explanation:

Length = letent heat

Discussion

13.	If two balls of same metal weighing 5 gm and 10 gm strike with a target with the same velocity. The heat energy so developed is used for raising their temperature alone, then the temperature will be higher(A) For bigger ball(B) For smaller ball(C) Equal for both the balls(D) None is correct from the above three
Answer» Correct option(C) Equal for both the balls Explanation: ∵metal same so specific heat is also same

13.

If two balls of same metal weighing 5 gm and 10 gm strike with a target with the same velocity. The heat energy so developed is used for raising their temperature alone, then the temperature will be higher(A) For bigger ball(B) For smaller ball(C) Equal for both the balls(D) None is correct from the above three

Answer»

Correct option(C) Equal for both the balls

Explanation:

∵metal same so specific heat is also same

Discussion

14.	The pressure is a bulb dropped from 2000 to 1500 mm of Hg in 47 minutes when the contained oxygen leaked through a small hole. The bulb was then completely evacuated A mixture of oxygen and another gas of molecular weight 79 n the molar ratio of 1: 1 at a total pressure of 4000 mm of mercury was introduced, find the molar ratio of the two gases remaining in the bulb after a period of 74 minutes.
Answer» rgas = 6.77 mm of Hg/min

14.

The pressure is a bulb dropped from 2000 to 1500 mm of Hg in 47 minutes when the contained oxygen leaked through a small hole. The bulb was then completely evacuated A mixture of oxygen and another gas of molecular weight 79 n the molar ratio of 1: 1 at a total pressure of 4000 mm of mercury was introduced, find the molar ratio of the two gases remaining in the bulb after a period of 74 minutes.

Answer»

rgas = 6.77 mm of Hg/min

Discussion

15.	A gas in an open container is heated from 27°C to 127°C. The fraction of the original amount of gas remaining in the container will be(A) 3/4(B) 1/2(C) 1/4(D) 1/8
Answer» Correct option(A) 3/4 Explanation :

15.

A gas in an open container is heated from 27°C to 127°C. The fraction of the original amount of gas remaining in the container will be(A) 3/4(B) 1/2(C) 1/4(D) 1/8

Answer»

Correct option(A) 3/4

Explanation :

Discussion

16.	Ebonite is(A) Natural rubber(B) Synthetic rubber(C) Higly vulcanized rubber(D) polypropene
Answer» (C) Higly vulcanized rubber

Discussion

Explore topic-wise InterviewSolutions in .

The enthalpies of neutralisation of a strong acid HA and weaker acid HB by NaOH are -13.7 and -12.7 kcal/eq. When one equivalent of NaOH is added to a mixture containing 1 equivalent of HA and HB; the enthalpy change was -13.5kcal. In what ratio is the base distributed between HA and HB?

Curves A and B describe the log P versus log V relation for helium, hydrogen, O3and PH3during adiabatic process. Curve C is for(A) He(B) H2(C) O3(D) PH3

Time period of a block when suspended from the upper plate of a parallel plate capacitor by a spring of stiffness k,is T,when block is uncharged. If a charge qis given to the block, then the new time period of oscillation will be(a) T(b) &gt; T(c) &lt; T(d)≥ T

A point performs SHM along a straight line with a period T = 0.60 s and amplitude a = 10 cm. Starting from extreme position, in what time, the point travels a distance a/2?(A) 10 s(B) 1.0 s(C) 0.1 s(D) 0.01 s

Which is least reactive towards nucleophilic substitution (SN2)

Acceleration-displacement graph of a particle executing SHM Is as shown in given figure. The time period of its oscillation is: (in sec)(A)π/2(B) 2π(C) π(D) π/4

Two rods of same material and thickness are joined as shown below. The ends X and Y are maintained at XºC and YºC respectivelythe ratio of heat flow at M and N are Q1 and Q2 respectively. Then –(A) Q1 = Q2(B) Q1 &gt; Q2(C) Q1 &lt; Q2(D) Q1 = Q2/2

A gas in an open container is heated from 27°C to 127°C. The fraction of the original amount of gas remaining in the container will be(A) 3/4(B) 1/2(C) 1/4(D) 1/8

Ebonite is(A) Natural rubber(B) Synthetic rubber(C) Higly vulcanized rubber(D) polypropene

Time period of a block when suspended from the upper plate of a parallel plate capacitor by a spring of stiffness k,is T,when block is uncharged. If a charge qis given to the block, then the new time period of oscillation will be(a) T(b) > T(c) < T(d)≥ T

Two rods of same material and thickness are joined as shown below. The ends X and Y are maintained at XºC and YºC respectivelythe ratio of heat flow at M and N are Q1 and Q2 respectively. Then –(A) Q1 = Q2(B) Q1 > Q2(C) Q1 < Q2(D) Q1 = Q2/2