﻿ Engineering Entrance Exam Question and Answers | Thermodynamics - Zigya

## Previous Year Papers

Download Solved Question Papers Free for Offline Practice and view Solutions Online.

## Test Series

Take Zigya Full and Sectional Test Series. Time it out for real assessment and get your results instantly.

## Test Yourself

Practice and master your preparation for a specific topic or chapter. Check you scores at the end of the test.

# Thermodynamics

#### Multiple Choice Questions

11.

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

• Te>T

• T >Te

• Te is 5 times T

• Te is 5 times T

290 Views

12.

Δ U is equal to

• Isochoric work

• Isobaric work

1808 Views

13.

Given
C(grahite) + O2(g) → CO2(g)
ΔrH°  = - 393.5 kJ mol-1
H2(g) + 1/2O2(g) → H2O (l)
ΔrH°  = +890.3 kJ mol-1
Based on the above thermochemical equations, the value of ΔrH° at 298 K for the reaction
C(grahite) + 2H2(g) →CH4 will be

•  +74.8 kJ mol–1

• +144.0 kJ mol–1

• –74.8 kJ mol–1

• –74.8 kJ mol–1

406 Views

14.

In a fuel cell methanol is used as fuel and oxygen gas is used as an oxidizer. The reaction is
CH3OH(l) + 3/2O2(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:

• 80%

• 97%

• 87%

• 87%

489 Views

15.

Which one of the following reactions of Xenon compounds is not feasible?

• XeO3+ 6HF → XeF6  + 3H2O

• 3XeF4 +6H2O → Xe+XeO3+ 12HF+ 1.5O2

• 2XeF2 + 2H2O → 2Xe + 4HF +O2

• 2XeF2 + 2H2O → 2Xe + 4HF +O2

208 Views

16.

Oxidising power of chlorine in aqueous solution can be determined by the parameters indicated below The energy involved in conversion of  • 152 kJ mol-

• -610 kJ mol-

• -850  kJ mol-

• -850  kJ mol-

264 Views

17.

Standard entropy of X2, Y2 and XY3 are 60, 40 and 50 JK−1
mol −1, respectively. For the reaction,1/2X2 + 3/2Y2, ΔH = -30 kJ,to be at equilibrium, the temperature will be

• 1250 K

• 500 K

• 750 K

• 750 K

392 Views

18.

In the reaction,
2Al(s) + 6HCl(aq) → 2Al3+ (aq) + 6Cl¯(aq) + 3H2(g)

• 6L HCl(aq) is consumed for every 3L H2(g) produced

• 33.6 L H2(g) is produced regardless of temperature and pressure for every mole Al that reacts

• 67.2 L H2(g) at STP is produced for every mole Al that reacts

• 67.2 L H2(g) at STP is produced for every mole Al that reacts

213 Views

19.

Identify the correct statement regarding a spontaneous process –

• For a spontaneous process in an isolated system, the change in entropy is positive

• Endothermic processes are never spontaneous

• Exothermic processes are always spontaneous

• Exothermic processes are always spontaneous

197 Views

20.

In the conversion of limestone to lime, CaCO3(s) → CaO(s) + CO2(g) the values of ∆Hº and ∆Sº are + 179.1 kJ mol–1 and 160.2 J/K respectively at 298K and 1 bar. Assuming that ∆Hº and ∆Sº do not change with temperature, temperature above which conversion of limestone to lime will be spontaneous is

• 1008 K

• 1200 K

• 845 K

• 845 K

180 Views