MCQs on Thermodynamics
1. What will be the value of ΔH, if the forward and reverse reactions have the same energy of activation?
(a) ΔH = ΔG = ΔS = 0
(b) ΔS = 0
(c) ΔG = 0
(d) ΔH = 0
Answer:::: (d)
4. What is the molar entropy change for melting of ice at 0℃, if ΔHf = 1.435 kcal/mol?
(a) 0.526 cal/(mol K)
(b) 5.26 cal/(mol K)
(c) 10.52 cal/(mol K)
(d) 21.04 cal/(mol K)
Answer:::: (b)
5. What is the function of a catalyst in a chemical reaction?
(a) decrease rate constant of reaction
(b) increases activation energy of reaction
(c) reduces enthalpy of reaction
(d) does not affect the equilibrium constant of reaction
Answer:::: (d)
6. What will be the work done by 3 moles of an ideal gas when it expands spontaneously in a vacuum?
(a) zero
(b) infinite
(c) 3 joules
(d) 9 joules
Answer:::: (a)
7. Find the temperature at which the below reaction will be in equilibrium if the enthalpy and entropy change for the reaction is 30 kJ mol-1 and 105 J K-1 mol-1 respectively
Br2(l) + Cl2(g) → 2BrCl(g)
(a) 273 K
(b) 300 K
(c) 450 K
(d) 285.7 K
Answer:::: (d)
8. Which is true for the entropy of a spontaneous reaction?
(a) ΔS(system) – ΔS(surroundings) > 0
(b) ΔS(system) + ΔS(surroundings) > 0
(c) ΔS(surroundings) > 0 only
(d) ΔS(system) > 0 only
Answer:::: (b)
9. An ideal gas is expanded isothermally at 300 K from 1 litre to 10 litres. Find the ΔE for this process (R = 2 cal mol-1 K-1)
(a) 9 L atm
(b) 1381.1 cal
(c) zero
(d) 163.7 cal
Answer:::: (c)
10. ΔH for the reaction N2 + 3H2 ⇋ 2NH3
(a) ΔE – 2RT
(b) ΔE + 2RT
(c) ΔE – RT
(d) ΔH = RT
Answer:::: (a)
