Which of the following compounds forms ortho-benzenedicarboxylic acid when oxidized by hot aqueous potassium permanganate?

In the nitration of benzene by mixed acid,the rate of reaction will be:

In the following reaction,
$CH_3-C \equiv CH \xrightarrow[873 \ K]{\text{red hot iron tube}} A$
the number of sigma$(\sigma)$ bonds present in the product $A$ is

Ring nitration of dimethylbenzene results in the formation of only one nitro dimethylbenzene. The dimethylbenzene is

The major product of the following reaction is:
$Glucose \xrightarrow[(ii) \ Mo_2O_3, \ 773 \ K, \ 10-20 \ atm]{(i) \ HI, \ \Delta} ?$

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