Class XI Chemistry IQs on Thermodynamics

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Question 1

Enthalpy of is negative. If enthalpy of combustion of and are x and y respectively. Then which of the following relations is correct?

• Ax > y
• Bx < y
• Cx = y
• Dx  y

Question 2

The energy absorbed by each molecule (A₂) of a substance is 4.4 x 10^-19 J and bond energy per molecule is 4.0 x 10^-19 J. The kinetic energy of the molecule per atom will be

• A2.0 X 10^-20 J
• B2.2 X 10^-19 J
• C2.0 X 10^-19 J
• D4.0 X 10^-20 J

Question 3

Standard enthalpy of vaporization for water at 100⁰C is 40.66 Kj mol^-1. The internal energy of vaporization of water at 100⁰C (in kJ mol^-1) is
(Assume water vapour to behave like an ideal gas).

• A+37.56
• B-43.76
• C+43.76
• D+40.66

Question 4

Considering entropy (S) as a thermodynamic parameter, the criterion for the spontaneity of any process is.

• A
• B
• C
• D

Question 5

The enthalpy of fusion of water is 1.435 kcal/mol. The molar entropy change for the melting of ice at 0^oC is

• A10.52 cal/(mol K)
• B21.04 cal/(mol K)
• C5.260 cal/(mol K)
• D0.526 cal/(mol K)

Question 6

A gas is allowed to expand in a well insulated container against a constant external pressure of 2.5atm from an initial volume of 2.50 L to a final volume of 4.50L. The change in internal energy U of the gas in joules will be:

• A-1136 J
• B-1505 J
• C-506 J
• D-510 J

Question 7

Assume each reaction is carried out in an open container. For which reaction will ΔH=ΔE ?

• AH₂(g) + Br₂(g) 2HBr(g)
• BC(s) + 2H₂O(g) 2H₂(g) + CO₂(g)
• CPCl₅(g) PCl₃(g)+ Cl₂(g)
• D2CO(g) + O₂ (g) 2CO₂(g)

Question 8

The correct thermodynamic conditions for the spontaneous reaction at all temperatures is

• AH > O and S< 0
• BH < O and S> 0
• CH < O and S< 0
• DH > 0 and S= 0

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