Question

Hot concentrated sulpuric acis is a moderatly strong oxidizing agent. Which of the following reaction does not shwo oxidizing behaviour?
A. `Cu + 2H_(2)SO_(4) rarr CuSO + SO_(2) + 2H_(2)O`
B. `3S + 2H_(2)SO_(4) rarr 3SO_(2) + 2H_(2)O`
C. `C + 2H_(2)SO_(4) rarr CO_(2) + 2SO_(2) + 2H_(2)O`
D. `CaF_(2) + H_(2)SO_(4) rarr CaSO_4) + 2HF`

Answer 1

Correct Answer - D
Key idea An oxidising agent is a species, which oxidises the other species and itself gets reduced.
(i) `Coverset(0)u+2H_(2)SO_(4) rarr overset(+2)(C)uSO_(4) + SO_(2) + 2H_(2)O`
(ii) `3underset(0)(S)+2H_(2)SO_(4) rarr 3overset(+4)(S)O_(2) + 2H_(2)O`
(iii) `overset(0)(C) + H_(2)SO_(4) rarr overset(+4)(CO_(2)) + 2SO_(2) + 2H_(2)O`
(iv) `overset(+2)(C)overset(-1)(F)_(2) + H_(2)SO_(4) rarr overset(+2)(C)aSO_(4) + 2Hoverset(-1)(F)`.
In reaction (iv), oxidation number of elements remains unchanged Thus, in this reaction, `H_(2)SO_(4)` does not act as an oxidising agent.