What is obtained by the reaction of $SO_2$ with an aqueous solution of sodium hydroxide?

In the manufacture of sulphuric acid by the contact process,the Tyndall box is used to

Statement $(A)$ Sulphur vapour is paramagnetic. Statement $(B)$ Reaction of dil. $HCl$ with finely divided iron forms $FeCl_3$ and $H_2$ gas. The correct answer is

The most abundant element in the Earth's crust is .............. .

Which of the following compounds produces an $oxy$-$acid$ having a basicity of $2$ upon hydrolysis?

White phosphorus reacts with sulphuryl chloride to form $PCl_5$ and $X$. Chlorine reacts with $X$ in the presence of wood charcoal to form $Y$. $X$ and $Y$ are respectively