Among the following, the anti-aromatic compound is:

In which of the following reactions is hydrogen gas not liberated:

(I) 

(II) 

(III) 

Arrange the following compounds in the order of decreasing reactivity towards electrophilic substitution reaction.

($\mathrm{I}$) 

($\mathrm{II}$) 

($\mathrm{III}$) 

($\mathrm{IV}$) 

Give the order of decreasing reactivity towards an electrophile.

$1.$ 

$2.$

$3.$

$4.$

$5.$