In which of the following reactions conc. `H_(2)SO_(4)` is used as an oxidising reagent?

Options

A. `CaF_(2)+H_(2)SO_(4)toCaSO_(4)+2HF`
B. `2HI+H_(2)SO_(4)toI_(2)+SO_(2)+2H_(2)O`
C. `Cu+2H_(2)SO_(4)toCuSO_(4)+SO_(2)+2H_(2)O`
D. `NaCl+H_(2)SO_(4)toNaHSO_(4)+HCl`

Answer

B, C

Explanation

In the above given four reactions, (b) and ( c) represent oxidising behaviour of `H_(2)SO_(4)`. As we know that oxidising agent reduces itself as oxidation state of central atom decreases. Here,
`overset(-1)2HI+H_(2)overset(-6)(SO_(4))tooverset(0)I_(2)+overset(-4)(SO_(2))+2H_(2)O`
`overset(0)Cu+2H_(2)overset(+6)SO_(4)tooverset(+2)CuSO_(4)+overset(+4)SO_(2)+2H_(2)O`