Question

Hydrazobenzene can be obtained from nitro benzene in the presence of:
(A) $Zn + KOH$
(B) $Zn + HCl$
(C) $Zn + ZnO$
(D) $Zn + {H_2}S{O_4}$

Answer 1

For solving this problem we should know the reactions of nitrobenzene. Nitrobenzene is acidic in nature so we have to study the properties of them as well. And we need to know all the possible ways to prepare hydrazobenzene. Then only we can be able to solve the above problem. And also consider the given reagents and their reaction with nitrobenzene to answer the question correctly.

Complete step-by-step answer: Nitrobenzene is an organic compound having the chemical formula ${C_6}{H_5}N{O_2}$. It is a water insoluble compound with almond like odour and a pale yellow outlook. Nitrobenzene is obtained from nitration of benzene. Nitration reaction occurs in presence of benzene and mixed acid (${H_2}S{O_4}$,${H_2}O$and$HN{O_3}$).

Hydrazobenzene is a derivative of hydrazine. It is a colorless crystal at room temperature. It is practically insoluble in water, slightly soluble in benzene, completely soluble in ethanol.
It is also called $1,2 - diphenylhydrazine$. It is an important chemical for industrial uses and also used widely in preparation of hydrogen peroxide.
If we talk about the reaction of nitrobenzene with $Zn + HCl$:
Nitrobenzene will be reduced in presence of $Zn + HCl$ and aniline will be produced.

If nitrobenzene is treated with $Zn$dust and ${H_2}S{O_4}$it will produce nitrosobenzene.

And finally, if we treat nitrobenzene with $Zn$dust and alcohol $KOH$we will get hydrazobenzene as a product.
${C_6}{H_5}N{O_2} + Zn\;Powder + alcoholicKOH \to {C_6}{H_5} - NH - NH - {C_6}{H_5}$

So, the answer will be option (A)

Note: considering all the reactions with nitrobenzene we will get the answer. $Zn$Dust and $KOH$and also sodium amalgam and carbon will be required for the completion of the reaction. In sodium amalgam it is necessary to have $0.1 - 0.2\%$sodium.