Nitrating mixture is

Which order is correct for the decreasing reactivity toward ring monobromination of the following compounds:
$I. \, C_6H_5CH_3$
$II. \, C_6H_5COOH$
$III. \, C_6H_6$
$IV. \, C_6H_5NO_2$

Which one of the following functional groups is not meta directing?

The total number of aromatic species generated in the following reactions is:

Identify the anti-aromatic compound.

For isomeric hydrocarbons with molecular formula $C_9H_{12}$ that give a negative Baeyer's test,determine the total number of isomers that possess four different non-aliphatic substitution sites.