Out of benzene, m-dinitrobenzene and toluene which will undergo nitration most easily and why?

How will you explain the directive influence of alkyl group (in the case of toluene)?

How will you explain the directive influence of –NH₂ group (in the case of aniline)?

How will you explain the directive influence of -CHO group?

How will you explain the directive influence of halogens?

Arrange the following set of compounds in order of their decreasing relative reactivity with an electrophile E⁺:

(a) Chlorobenzene; 2, 4-dinitrochlorobenzene, p- nitro chlorobenzene

What are polynuclear hydrocarbons? Discuss the toxicity of polynuclear hydrocarbons.

What is liquified petroleum gas (L.P.G.)?

Discuss measures for the control of pollution problems with special reference to the use of C.N.G.