Which is the correct thermal stability order for $H_2 E$ $(E = O, S, Se, Te, Po)$?

When sulphur is boiled with $Na_2SO_3$,a compound $(A)$ is produced. $(A)$ on reaction with excess $AgNO_3$ solution gives a compound $(B)$,which after dissolving in water produces a black coloured sulphide $(C)$. Identify the compound $(A)$,$(B)$ and $(C)$.

The most efficient agent for the absorption of $SO_3$ is

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

What is formed when $H_2S$ reacts with $O_2$?

Which among the following is $NOT$ the use of $SO_2$ gas?