When $KBr$ is treated with conc. $H_2SO_4$,a reddish-brown gas is evolved. The evolved gas is:

Why is $ICl$ more reactive than $I_2$?

Justify,by giving reactions,that among halogens,fluorine is the best oxidant and among hydrohalic compounds,hydroiodic acid is the best reductant.

The bond dissociation energies of $F_2, Cl_2, Br_2$ and $I_2$ are $155, 244, 193$ and $151 \ kJ \ mol^{-1}$ respectively. Which of these has the weakest bond?

$POCl_3$ is prepared by the reaction of:
$(I)$ $P_4 + SO_2Cl_2 \to$
$(II)$ $P_4 + SOCl_2 \to$
$(III)$ $PCl_5 + SO_2 \to$
$(IV)$ $PCl_5 + C_2H_5OH \to$

Which of the following reactions is not feasible?