Chemistry, Thermodynamics MCQs | Questions – Paper 2

Identify the correct statement from the following in a chemical reaction. [West Bengal JEE 2012]

For the reversible reaction,

A_(s) + B_(g)  C_(g) + D_(g) ΔG° = -350kJ,

which one of the following statements is true? [Karnataka CET 2011]

The enthalpy of vaporization of benzene is +35.3 kJ/mol at its boiling point of 80°C. The entropy change in the transition of vapour to liquid at its boiling point is ______. (in J mol⁻¹ K⁻¹) [Karnataka CET 2011]

The entropy change involved in the isothermal reversible expansion of 2 moles of an ideal gas from a volume of 10 dm³ to a volume of 100 dm³ at 27°C is [AIEEE 2011]

In view of the signs of Δ_rG° for the following reactions

PbO₂ + Pb → 2 PbO, Δ_rG° < 0

SnO₂ + Sn → 2 SnO, Δ_rG° > 0,

Which oxidation states are more characteristic for lead and tin? [AIEEE 2011]

The Gibbs energy for the decomposition Al₂O₃ at 500°C is as follows:

Al₂O₃ → Al + O₂, Δ_rG = +966kJ mol^–1

The potential difference needed for electrolytic reduction of Al₂O₃ at 500°C is at least [AIEEE 2010]

For a particular reversible reaction at temperature T, ΔH and ΔS were found to be both +ve. If T_e is the temperature at equilibrium, the reaction would be spontaneous when [AIEEE 2010]

On the basis of the following thermochemical data:

(ΔfG°H⁺_(aq) = 0)

H₂O(l) → H⁺ (aq) + OH⁻ (aq); ΔH = 57.32 kJ

H₂ (g) + O₂(g) → H₂O(l) ΔH = −286.20kJ

The value of enthalpy of formation of OH⁻ ion at 25°C is : [AIEEE 2009]

In a fuel cell methanol is used as fuel and oxygen gas is used as an oxidizer. The reaction is

CH₃OH(l) +  O₂(g) → CO₂(g) + 2H₂O(l)

At 298 K standard Gibb's energies of formation for CH₃OH(l), H₂O(l) and CO₂(g) are –166.2, –237.2 and –394.4 kJ mol^–1 respectively. If standard enthalpy of combustion of methanol is –726 kJ mol^–1, efficiency of the fuel cell will be [AIEEE 2009]

One mole of which of the following has the highest entropy? [Karnataka CET 2008]

When compared to ΔG° for the formation of Al₂O₃, the ΔG° for the formation of Cr₂O₃ is [Karnataka CET 2008]

Standard entropy of X₂, Y₂ and XY₃ are 60, 40 and 50JK⁻¹mol⁻¹, respectively.

For the reaction, X₂ + Y₂ → XY₃, ΔH = -30kJ, to be at equilibrium, the temperature will be [AIEEE 2008]

Entropy of the universe is [Karnataka CET 2007]

In which of the following process, a maximum increase in entropy is observed? [Karnataka CET 2007]

ΔH_vap = 30 KJ/mole and ΔS_vap = 75 Jmol^–1K^–1. Find temperature of vapour, at one atmosphere [IIT JEE 2004]