The maximum number of molecule is present in

• 15 L of H₂ gas at STP

• 5 L of N₂ gas at STP

• 0.5 g of H₂ gas

• 10 g of O₂ gas

The work done during the expansion of a gas from a volume of 4 dm³ to 6 dm³ against a constant external pressure of 3 atm, is

• -6 J

• -608 J

• +304 J

• -304 J

Born-Haber cycle may be used to calculate

• electronegativity

• mass number

• oxidation number

• electron affinity

The heat of formation for CO₂ (g), H₂O (l) and CH₄ (g) are -400 kJ mol^-1, -280 kJ mol^-1 and -70 kJ mol^-1 respectively. The heat of combustion of CH₄ in kJ mol^-1 is

• 890

• -160

• -890

• -90

C (s) + O₂ (g) → CO₂ (g); $∆$H = -94kcal

2CO (g) + O₂ (g) → 2CO₂ (g); $∆$H = -135 kcal.

The heat of formation of CO (g) is

• -26.4 kcal

• 41.2 kcal

• 26.4 kcal

• 229.2 kcal

The entropy of a perfectly crystalline material is zero at 0°C. This is statement of

• first law of thermodynamics

• second law of thermodynamics

• third law of thermodynamics

• law of conservation of energy

In any chemical reaction, a quantity that decrease to a minimum is

• free energy

• entropy

• temperature

• enthalpy

Given, H₂O (l) → H₂O (g); $∆$H₁ = +43 kJ

H₂O (s) → H₂O (l); $∆$H₂ = +6.05 kJ. Calculate the enthalpy of sublimation of ice.

• 49.75 kJ mol^-1

• 37.65 kJ mol^-1

• 43.7 kJ mol^-1

• 55.23 kJ mol^-1

If standard enthalpies of formation of CaCl (s) (hypothetical) and that of CaCl₂ (s) are -188 J mol^-1 and -795 kJ mol^-1 respectively, calculate the value of standard heat of reaction for the following  disproportionation reaction

2CaCl (s) → CaCl₂ (s) + Ca (s)

• -607 kJ mol^-1

• +607 kJ mol^-1

• -419 kJ mol^-1

• +419 kJ mol^-1

Heat formation of H₂O is -188 kJ/ mol and H₂O₂ is 286 kJ/mol. The enthalpy change for the reaction; 2H₂O₂ → 2H₂O + O₂ is

• 196 kJ

• -196 kJ

• 984 kJ

• -984 kJ