91Ó°ÊÓ

In the estimation of sulphur by Carius method, \(0.468 \mathrm{~g}\) of an organic sulphur compound afforded \(0.668 \mathrm{~g}\) of barium sulphate. Find out the percentage of sulphur in the given compound.

In the organic compound \(\mathrm{CH}_{2}=\mathrm{CH}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{C} \equiv \mathrm{CH}\), the pair of hydridised orbitals involved in the formation of: \(\mathrm{C}_{2}-\mathrm{C}_{3}\) bond is: (a) \(s p-s p^{2}\) (b) \(s p-s p^{3}\) (c) \(s p^{2}-s p^{3}\) (d) \(s p^{3}-s p^{3}\)

In the Lassaigne's test for nitrogen in an organic compound, the Prussian blue colour is obtained due to the formation of: (a) \(\mathrm{Na}_{4}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]\) (b) \(\mathrm{Fe}_{4}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]_{3}\) (c) \(\mathrm{Fe}_{2}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]\) (d) \(\mathrm{Fe}_{3}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]_{4}\)

Which of the following carbocation is most stable? (a) \(\left(\mathrm{CH}_{3}\right)_{3} \mathrm{C} . \mathrm{C} \mathrm{H}_{2}\) (b) \(\left(\mathrm{CH}_{3}\right)_{3} \mathrm{C}\) (c) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{C} \mathrm{H}_{2}\) (d) \(\mathrm{CH}_{3} \mathrm{C} \mathrm{H} \mathrm{CH}_{2} \mathrm{CH}_{3}\)

The best and latest technique for isolation, purification and separation of organic compounds is: (a) Crystallisation (b) Distillation (c) Sublimation (d) Chromatography

The reaction: \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{I}+\mathrm{KOH}(\mathrm{aq}) \rightarrow \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}+\mathrm{KI}\) is classified as : (a) electrophilic substitution (b) nucleophilic substitution (c) elimination (d) addition