16.Calculate the entropy change in melting 1 mole of ice at 273K. $ΔH_f^\circ$ = 6.025kJ/mol A) 11.2 J/Kmol B) 22.1J/Kmol C) 15.1 J/Kmol D) 5.1 J/Kmol View Answer Report DiscussAnswer: Option BExplanation:$ΔS_{f} = \frac{ΔH_{f}}{T}$ = $\frac{6025 Jmol^{-1}}{273 K}$ = 22.1J/Kmol
17.An organic compound 'A' has the molecular formula C3H6O it undergoes the iodoform test. When saturated with dil. HCl gives 'B' of molecular formula C9H14O. A and B respectively are A) Propanal and mesitylene B) Propanone and mesityl oxide C) Propanone and 2,6- dimethyl-2, 5-heptadien-4-one D) Propanone and mesitylene oxide View Answer Report DiscussAnswer: Option CExplanation:Compound A with formula C3H6O gives an iodoform test, it is propanone. It forms a compound B having carbon atoms three times to the number of carbon atoms in propanone, it is 2, 6-dimethyl-2, 5-heptadien-4-one.
18.Which element gives the maximum number of oxides? A) V B) Cr C) Mn D) Fe View Answer Report DiscussAnswer: Option CExplanation:Among the transition metals, Mn forms the maximum no. of oxides. MnO(basic) Mn3O4 (amphoteric) Mn2O3 ( amphoteric) MnO2 (amphoteric) Mn2O7(acidic)
19.The reaction 2NO(g) + O2(g) → 2NO2(g) is of the first order If volume of the reaction vessel is reduced to 1/3, the rate of reaction would be A) 1/3 times B) 2/3 times C) 3 times D) 6 times View Answer Report DiscussAnswer: Option CExplanation:For following reaction, 2NO(g) + O2(g) → 2NO2(g) When the volume of the vessel is reduced to 1/3 then the concentration of the reactant becomes three times. The rate of reaction for the first-order reaction is proportional to the concentration. So the rate of reaction will increase three times.
20.Bragg's law is given by which of the following equation? A) $n\lambda = 2\theta\sin\theta$ B) $n\lambda = 2d\sin\theta$ C) $2n\lambda = d\sin\theta$ D) $ n\frac{\theta}{2} = \frac{d}{2}\sin\theta$ View Answer Report DiscussAnswer: Option BExplanation:$n\lambda = 2d\sin\theta$
