Which product is obtained by the dehydration of concentrated $H_2SO_4$ in the presence of $P_4O_{10}$?

In which of the following is the formation of polyanions maximum?

Which of the following oxyacids of sulphur contains both $S=S$ and $S=O$ bonds?

Given below are two statements: Statement $I$: The covalency of oxygen is generally two but it can exceed up to four. The oxidation state of oxygen in $SO_2$ is $-2$ and in $OF_2$ it is $+2$. Statement $II$: The anomalous behaviour of oxygen when compared to the other elements of group $16$ is due to its small size and high electronegativity. In the light of the above statements, choose the correct answer from the options given below.

Which of the following elements is $NOT$ a member of group $16$ of the periodic table?

What are the products formed when ferrous sulphate $(FeSO_4 \cdot 7H_2O)$ is heated strongly?