What is the difference between ΔH and ΔU for the combustion of benzoic acid (C₇H₆O₂) at 300 K?

1. -1.247 kJ

2. +1.247 kJ

3. -1.247 J

4. +1.247 J

When 4 g of iron is burnt in oxygen to form ferric oxide at constant pressure, 29.28 kJ of heat is evolved. Calculate the enthalpy of formation of ferric oxide.

(At. mass of Fe = 56) ?

1. $-$81.98 kJ

2. $-$ 819.8 kJ

3. $-$ 40.99 kJ

4.  +819.8 kJ

The maximum work done in expanding 16g ${\mathrm{O}}_2$ isothermally at 300 K and occupying a volume of
5 dm³ until the volume becomes 25 dm³ is:

1. –2.01$\times {10}^3$ J

2. 2.01×${10}^{-3}$ J

3. +2.81$\times {10}^3$ J

4. +2.01$\times {10}^{-6}$J

 Which of the following conditions will always lead to a non-spontaneous change?

1. Positive \(~\Delta H\) and positive \(~ \Delta S\)
2. Negative \(~\Delta H\) and negative \(~ \Delta S\)
3. Positive\(~\Delta H\)and negative \(~ \Delta S\)
4. Negative\(~\Delta H\) and positive\(~ \Delta S\)

To calculate the amount of work done in joules during reversible isothermal expansion of an ideal gas, the volume must be expressed in:

Which of the following is the correct sign of entropy change (ΔS) for the conversion:

C(graphite) → C(diamond)

1. Zero

2. Positive

3. Negative

4. Cannot be determined from given data

Calculate the entropy change when one mole of liquid water at 373 K is converted into water vapour at the same temperature.

Given: Latent heat of vaporisation of water, ΔHᵥₐₚ = 2.257 kJ g⁻¹.

1. 105.9 JK^-1mol^-1

2. 107.9 JK^-1mol^-1

3. 108.9 JK^-1mol^-1

4. 109.9 JK^-1mol^-1

\(\underset {-10.7 \mathrm{JK}^{-1}{mol}^{-1}} {\mathrm{H}_{(a q)}^{+}+\mathrm{OH^{-}}_{(a q)}} \rightarrow \underset {+70 \mathrm{JK}^{-1} \mathrm{~mol}^{-1} } {\mathrm{H}_{2} \mathrm{O}_{(l)}} ~~ \mathrm{S}^{\circ}(298 \mathrm{~K})\)

Standard entropy change for the above reaction is:

1. 60.3 JK^-1 mol^-1

2. 80.7 JK^-1 mol^-1

3. -70 JK^-1 mol^-1

4. +10.7 JK^-1 mol^-1

Hydrolysis of sucrose is given by the following reaction

Sucrose + H₂O $\rightleftharpoons$ Glucose + Fructose

If the equilibrium constant (K_c) is 2$\times$10¹³ at 300 K, the value of ${∆}_r{G}^{⊝}$ at the same temperature will be:

1. 8.314 J mol^–1 K^–1$\times$300 K$\times$ln (2$\times$10¹³)

2. 8.314 J mol^–1 K^–1$\times$300 K$\times$ln (3$\times$10¹³)

3. –8.314 J mol^–1 K^–1$\times$300 K$\times$ln (4$\times$10¹³)

4. –8.314 J mol^–1 K^–1$\times$300 K$\times$ln (2$\times$10¹³)