21.For the reaction $H_{2}(g) + \frac{1}{2}O_{2}(g)\rightarrow H_{2}O(l)$.ΔH = - 285.8 kJ/mol, ΔS = - 0.163kJ/molK.What is the value of free energy change at 27°C for the reaction? A) -236.9kJ/mol B) -281.4kJ/mol C) -334.7kJ/mol D) +334.7kJ/mol View Answer Report DiscussAnswer: Option AExplanation:ΔG = ΔH - TΔS T = 27+273 = 300K ΔG = (-285.8) - 300(-0.163) kJ/mol = -236.9kJ/mol
22.Copper sulfate solution reacts with KCN to give A) $Cu(CN)_{2}$ B) CuCN C) $ K_{2}[Cu(CN)_{4}]$ D) $K_{3}[Cu(CN)_{4}]$ View Answer Report DiscussAnswer: Option DExplanation:$CuSO_{4} + 2KCN \rightarrow Cu(CN)_{2} + K_{2}SO_{4}$ $2Cu(CN)_{2} \rightarrow Cu_{2} (CN)_{2}$ OR $2CuCN+CN-CN_{cyanogen}$ $CuCN+ 3KCN \rightarrow K_{3}[Cu(CN)_{4}]_{Colourless}$
23.In a closed insulated container a liquid is stirred with a paddle to increase its temperature. In this process which of the following is true? A) $\triangle E = W = Q = 0$ B) $\triangle E \neq 0, Q = W = 0$ C) $\triangle E = W \neq 0, Q= 0$ D) $\triangle E = Q \neq 0, W = 0$ View Answer Report DiscussAnswer: Option CExplanation:As the system is closed and insulated, no heat enters. or leaves the system, i.e. Q = 0: ΔE = Q+W = W
24.What is X in the following change? A) $CH_{3}OH,H_{2}SO_{4}$ B) $CH_{3}OH,CH_{3}\overline{O}N^{+}a$ C) $H_{2}O/H_{2}SO_{4}$ followed by $CH_{3}OH$ D) $CH_{3}MgBr/H_{3}O^{+}$ View Answer Report DiscussAnswer: Option AExplanation:
25.Ethylene glycol, on oxidation with periodic acid, gives A) Oxalic acid B) Glycol C) Formaldehyde D) Glycolic acid View Answer Report DiscussAnswer: Option CExplanation:
