Which of the following reactions is a decomposition reaction ?

Options

A. HCl + NaOH `to ` NaCl + `H_2O`
B. `Zn+CuSO_4 to ZnSO_4 + Cu`
C. `2HgO oversetDeltato 2Hg+O_2`
D. `CO_2 + H_2O to H_2CO_3`

Answer

C

Explanation

The first reaction `CO_2 + H_2O to H_2CO_3` is a synthesis reaction.
The second reaction `2HgO to 2Hg + O_2 uarr` is decomposition reaction.
The third reaction `Zn+CuSO_4 to ZnSO_4 +Cu` is single replacement reaction.
The fourth reaction `HCl + NaOH to NaCl + H_2O` is a double replacement reaction (as well as a neutralization or acid-base reaction)