21. Heat of transition is the heat evolved or absorbed, when a substance is converted from
Vapor to liquid
Vapor to solid
Solid to liquid
One allotropic form to another allotropic form
✅ The correct answer is option D.
Statiometery MCQs
22. The value of the gas-law constant ‘R’ is 1.987
Kcal/kg-mole.°C
Btu/lb-mole.°R
Kcal/kg-mole.°K
Both B & C
✅ The correct answer is option D.
23. A gas at 0°C was subjected to constant pressure cooling until its volume became half the original volume. The temperature of the gas at this stage will be
0°C
0°K
-136.5°C
-136.5°K
✅ The correct answer is option C.
24. At higher temperatures, molal heat capacities for most of the gases (at constant pressure) __________ with increase in temperature.
Varies linearly
Increases
Decreases
Does not vary
✅ The correct answer is option B.
25. The heat change for the reaction, C(s) + 2S(s) → CS₂(l), is 104.2 kJ. It represents the heat of
Formation
Solution
Combustion
Fusion
✅ The correct answer is option A.
26. One mole of methane undergoes complete combustion in a stoichiometric amount of air. The reaction proceeds as CH₄ + 2O₂ → CO₂ + 2H₂O. Both the reactants and products are in gas phase. ΔH°298 = – 730 kJ/mole of methane. Mole fraction of water vapour in the product gases is about
0.19
0.33
0.4
0.67
✅ The correct answer is option A.
27. 2 litres of nitrogen at N.T.P. weighs __________ gms.
14
2.5
28
1.25
✅ The correct answer is option B.
28. If the pH value of a solution changes by one unit, it implies that hydrogen ion concentration in the solution will change __________ times.
10
20
70
100
✅ The correct answer is option A.
29. The unit of specific heat at constant pressure, Cp, in SI unit is
W/m²°C
J/kg°K
W/m°K
J/m³°K
✅ The correct answer is option B.
30. For estimation of heat capacity of a solid compound, one can use
Clayperon’s equation
Gibb’s equation
Kopp’s rule
Trouton’s rule
✅ The correct answer is option C.