Which of the following is/are produced when a mixture of benzene vapour and oxygen is passed over $V_2O_5$ catalyst at $775\, K$?

Benzene can be obtained in the reaction:

The product obtained by the reaction of benzene with concentrated $HNO_3$ and concentrated $H_2SO_4$ at $353$ to $363 \, K$ is....

In chlorination of benzene,the reactive species is

The number of $-CH_2-$ (methylene) groups in the product formed from the following reaction sequence is. . . . . . .

In which of the following reactions,$t$-butyl benzene is formed?
$1.$ Benzene $+ t$-butyl chloride $\xrightarrow{AlCl_3}$
$2.$ Benzene $+ (CH_3)_2C=CH_2 \xrightarrow{BF_3/HF}$
$3.$ Benzene $+ t$-butyl alcohol $\xrightarrow{H_2SO_4}$
$4.$ Benzene $+$ butanoyl chloride $\xrightarrow{AlCl_3}$ $\xrightarrow{Zn/Hg, HCl}$