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

Choose the correct statements from the following:
$A$. All group $16$ elements form oxides of general formula $EO_2$ and $EO_3$ where $E=S, Se, Te$ and $Po$. Both the types of oxides are acidic in nature.
$B$. $TeO_2$ is an oxidising agent while $SO_2$ is reducing in nature.
$C$. The reducing property decreases from $H_2S$ to $H_2Te$ down the group.
$D$. The ozone molecule contains six lone pairs of electrons.
Choose the correct answer from the options given below:

How many stages are there in the Contact Process,and what is produced at the end of the Contact Process?

In the presence of moisture,$SO_2$ can

Explain why ozone $(O_3)$ is thermodynamically less stable than oxygen $(O_2)$?

The oxoacid of sulphur which contains two sulphur atoms in different oxidation states is