Which of the following halogens combines with dihydrogen at the lowest temperature?

Identify the correct pairs in which the chemical substance given is correctly matched with its use.

Chemical substance	Use
$A. Cl_2$	Preparation of phosgene
$B. I_2O_5$	Estimation of $CO$
$C. O_3$	Disinfectant

Among the following,which is the strongest oxidising agent?

The strongest acid amongst the following is:

In aqueous solution, fluorine is a stronger oxidizing agent than chlorine. This is due to all of the following factors $EXCEPT$:

$A$ greenish-yellow gas reacts with an alkali metal hydroxide to form a halide that is used in the manufacture of safety matches and fireworks. Identify the gas and the halide,respectively.