Chemistry Class 11 NCERT Solutions: Chapter 6 Thermodynamics Part 1

Q: 1. Choose the correct answer. A thermodynamic state function is a quantity

(i) Used to determine heat changes

(ii) Whose value is independent of path

(iii) used to determine pressure volume work

(iv) Whose value depends on temperature only

Answer:

A thermodynamic state function is a quantity whose value is independent of a path. Functions like p, V, T etc. depend only on the state of a system and not on the path. Hence, alternative (ii) is correct.

Q: 2. For the process to occur under adiabatic conditions, the correct condition is:

Equation

Equation

Equation

Equation

Answer:

A system is said to be under adiabatic conditions if there is no exchange of heat between the system and its surroundings. Hence, under adiabatic conditions, q=0,

Therefore, alternative (iii) is correct.

Q: 3. The enthalpies of all elements in their standard states are:

(i) Unity

(ii) Zero

(iii) < 0

(iv) Different for each element

Answer:

The enthalpy of all elements in their standard state zero

Therefore, alternative (ii) is correct.

Q: 4. Equation

(i) Equation

(ii) Equation

(iii) Equation

(iv) Equation

Since Equation

Equation

Equation

Therefore, alternative (iii) is correct.

Q: 5. the enthalpy of combustion of methane, graphite and dihydrogen at Equation and Equation respectively. Enthalpy of formation of Equation will be

(i) Equation

Equation

(iii) Equation

(iv) Equation

Answer:

According to the question,

(i) Equation

Equation

(ii) Equation

Equation

(iii) Equation

Equation

Thus, the desired equation is the one that represents the formation of Equation i.e.,

Equation

Equation

Equation

Equation

Equation

Hence, alternative (i) is correct.

Q: 6. A reaction, Equation is found to have positive entropy change. The reaction will be

(i) Possible at high temperature

(ii) Possible only at low temperature

(iii) Not possible at any temperature

(iv) Possible at any temperature

Answer:

For a reaction to be spontaneous, Equation should be negative.

Equation

According to the question, for the given reaction,

Equation

Equation

Equation

Therefore, the reaction is spontaneous at any temperature.

Hence, alternative (iv) is correct.

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