Question

What happens when concentrated nitric acid reacts with
a) Bismuth
b) Benzene
c) Hydrogen sulphide

Answer 1

We have to remember that the concentrated nitric acid is a very strong acid. The pure form of the compound is highly corrosive in nature and is colorless. It has a high commercial value and it's $68\%$ solution is used for commercial purposes.

Complete answer:
We need to know that the bismuth is a metal with slight silver lustre and pink appearance. Whenever a strong acid reacts with metal, metal nitrates are formed and hydrogen gas is liberated.
This reaction is used to define the chemical property of metals and for their differentiation.
So, on reacting nitric acid with the metal that is bismuth a compound called bismuth nitrate is formed and hydrogen gas is liberated. The hydrogen gas liberated can be identified by pop sound when brought in contact with a matchstick.
Benzene on reaction with nitric acid results in the nitro group being attached to the benzene ring.
This reaction is called nitration.
Hydrogen sulphide is the hydride of non-metal sulphur .Hydrogen sulphide on reaction with nitric acid results in formation of Nitrogen dioxide and sulphur. The nitrogen atom combines with the oxygen and forms nitrogen dioxide while the hydrogen from hydrogen sulphide gets removed and sulphur gets oxidized.
It is an example of a redox reaction.
The sulphur is getting oxidised to zero state and the gas is liberated, that is nitrogen dioxide.

Note:
We must remember that the hydrogen sulphide is an important inorganic compound and is used in qualitative analysis of cations. Hydrogen sulphide has large application in application chemistry and has wide use in experiments.