Chemistry Class-11: Chapter –6. Thermodynamics Part – 3

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Question: 14

Which of the following is not correct?

(i) is zero for a reversible reaction

(ii) is positive for a spontaneous reaction

(iii) is negative for a spontaneous reaction

(iv) is positive for a non-spontaneous reaction

Answer: (ii)

II. Multiple Choice Questions (Type-II)

In the following questions two or more options may be correct.

Question: 15

Thermodynamics mainly deals with

(i) Interrelation of various forms of energy and their transformation from one form to another.

(ii) Energy changes in the processes which depend only on initial and final states of the microscopic systems containing a few molecules.

(iii) How and at what rate these energy transformations are carried out.

(iv) The system in equilibrium state or moving from one equilibrium state to another equilibrium state.

Answer: ( i), (iv)

Question: 16

In an exothermic reaction, heat is evolved, and system loses heat to the surrounding. For such system

(i) will be negative

(ii) will be negative

(iii) will be positive

(iv) will be positive

Answer: ( i), (ii)

Question: 17

The spontaneity means, having the potential to proceed without the assistance of external agency. The processes which occur spontaneously are

(i) Flow of heat from colder to warmer body.

(ii) Gas in a container contracting into one corner.

(iii) Gas expanding to fill the available volume.

(iv) Burning carbon in oxygen to give carbon dioxide.

Answer: (iii), (iv)

Question: 18

For an ideal gas, the work of reversible expansion under isothermal condition can be calculated by using the expression

A sample containing of an ideal gas is expanded isothermally and reversibly to ten times of its original volume, in two separate experiments. The expansion is carried out at and at respectively. Choose the correct option.

(i) Work done at is times the work done at .

(ii) Work done at is twice the work done at .

(iii) Work done at is twice the work done at .

(iv) in both cases.

Justification

For isothermal expansion of ideal gases,

Since temperature is constant this means there is no change in internal energy. Therefore, ΔU = 0

Answer: (iii), (iv)

Question: 19

Consider the following reaction between zinc and oxygen and choose the correct options out of the options given below:

(i) The enthalpy of two moles of is less than the total enthalpy of two moles of Zn and one mole of oxygen by .

(ii) The enthalpy of two moles of is more than the total enthalpy of two moles of and one mole of oxygen by .

(iii) energy is evolved in the reaction.

(iv) energy is absorbed in the reaction.

Answer: (i), (ii)

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