16.t-butyl can't give decarboxylation while normally $\alpha$-$\beta$ unsaturated acid give this reaction because A) t-butyl gp. has large size and does not let the COOH group to leave B) t-butyl gp. cannot extract H from COOH C) t-butyl gp. stabilise carbanion formed D) t-butyl gp. does not allow this composition to convert to $\beta-\gamma$ -unsaturated acid View Answer Report DiscussAnswer: Option CExplanation: Because of the +1 effect, the t-butyl group destabilises the carbanion
17.Group 15 elements have more electrons gain enthalpy than group 16 -elements.The correct reason for this is A) Half-filled stability of gp.15 elements B) poor shielding in gp.15 C) poor shielding in gp.16 D) half-filled stability ogf gp.16 elements View Answer Report DiscussAnswer: Option AExplanation: The atoms having half-filled and fully filled orbitals are comparatively more stable hence more energy is required to remove the electron from such atoms. Therefore group 15 have more I.E than gp.16 elements
18. For a reaction A → B: $\triangle$ H =20kj mol-1 the activation energy of the forward reaction is 85kJ/mol. The activation energy of the backward reaction will be A) 105 kJ/mol B) 65 kJ/mol C) 45 kJ/mol D) 75 kJ/mol View Answer Report DiscussAnswer: Option BExplanation:Energy of activation for forward reaction (Ea) =85 kj/mol $\therefore$ Energy of activation for backward reaction = Ea - $\triangle$ H=85-20=65 kJ mol-1
19.One mole of an ideal gas at 300 k is expanded isothermally from an initial volume of 1 litre to 10 litres. Then $\triangle$ S (cal deg-1 mol-1) for this process is : (R=2 cal K-1 mol-1) A) 7.12 B) 8.314 C) 4.6 D) 3.95 View Answer Report DiscussAnswer: Option CExplanation:For an isothermal process $\triangle S= 2.303 nR \log\frac{V_{2}}{V_{1}}$ $\triangle S= 2.303 \times1\times2\times\log \frac{10}{1}$ = 4.6 cal deg-1 mol-1
20.The protein Present in the hair is A) Lysine B) Myosine C) Keratin D) Alanine View Answer Report DiscussAnswer: Option CExplanation:Keratin
