System, surroundings, state functions and properties — practice questions

Question 1 · difficulty L2 · understanding

Among the following the number of state variables is ______________. Internal energy (U) Volume (V) Heat (q) Enthalpy (H)

Question 2 · difficulty L2 · understanding

When 5 moles of He gas expand isothermally and reversibly at 300 K from 10 litre to 20 litre, the magnitude of the maximum work obtained is __________ J. [nearest integer] (Given : R = 8.3 J K $$-$$1 mol $$-$$1 and log 2 = 0.3010)

Question 3 · difficulty L2 · understanding

What happens when methane undergoes combustion in systems A and B respectively?

• A. System A System B Temperature falls Temperature rises
• B. System A System B Temperature rises Temperature remains same
• C. System A System B Temperature falls Temperature remains same
• D. System A System B Temperature remains same Temperature rises

Question 4 · difficulty L2 · understanding

Which of the following relations are correct? (A) $$\mathrm{\Delta U=q+p\Delta V}$$ (B) $$\mathrm{\Delta G=\Delta H-T\Delta S}$$ (C) $$\Delta \mathrm{S}=\frac{q_{rev}}{T}$$ (D) $$\mathrm{\Delta H=\Delta U-\Delta nRT}$$ Choose the most appropriate answer from the options given below :

• A. A and B only
• B. B and C only
• C. C and D only
• D. B and D only

Question 5 · difficulty L2 · understanding

Which of the following relation is not correct?

• A. $$\Delta \mathrm{H}=\Delta \mathrm{U}-\mathrm{P} \Delta \mathrm{V}$$
• B. $$\Delta \mathrm{U}=\mathrm{q}+\mathrm{W}$$
• C. $$\Delta \mathrm{S}_{\text {sys }}+\Delta \mathrm{S}_{\text {surr }} \geqslant 0$$
• D. $$\Delta \mathrm{G}=\Delta \mathrm{H}-\mathrm{T} \Delta \mathrm{S}$$

Question 6 · difficulty L2 · understanding

Match List-I with List-II. List - I List - II (A) Spontaneous process (I) $$\Delta H < 0$$ (B) Process with $$\Delta P = 0$$, $$\Delta T = 0$$ (II) $$\Delta {G_{T,P}} < 0$$ (C) $$\Delta {H_{reaction}}$$ (III) Isothermal and isobaric process (D) Exothermic Process (IV) [Bond energies of molecules in reactants] $$-$$ [Bond energies of product molecules Choose the correct answer from the options given below :

• A. (A) - (III), (B) - (II), (C) - (IV), (D) - (I)
• B. (A) - (II), (B) - (III), (C) - (IV), (D) - (I)
• C. (A) - (II), (B) - (III), (C) - (I), (D) - (IV)
• D. (A) - (II), (B) - (I), (C) - (III), (D) - (IV)

Question 7 · difficulty L2 · understanding

The pair of isochoric processes among the transformation of states is

• A. K to L and L to M
• B. L to M and N to K
• C. L to M and M to N
• D. M to N and N to K

Question 8 · difficulty L2 · understanding

One mole of an ideal gas is taken from $\mathbf{a}$ to $\mathbf{b}$ along two paths denoted by the solid and the dashed lines as shown in the graph below. If the work done along the solid line path is $W_{\text {s }}$ and that dotted line path is $W_{\mathrm{d}}$, then the integer closest to the ratio $W_{\mathrm{d}} / W_{\mathrm{s}}$ is

Question 9 · difficulty L2 · understanding

Among the following, the state function(s) is(are)

• A. Internal energy.
• B. Irreversible expansion work.
• C. Reversible expansion work.
• D. Molar enthalpy.

Question 10 · difficulty L3 · understanding

The heat of combustion of solid benzoic acid at constant volume is $$-321.30 \mathrm{~kJ}$$ at $$27^{\circ} \mathrm{C}$$. The heat of combustion at constant pressure is $$(-321.30-x \mathrm{R}) \mathrm{~kJ}$$, the value of $$x$$ is __________.