Why is `H_(2)O` a liquid and `H_(2)S` a gas ?

Explanation

O is more electronegative than S, hence `H_2O` undergoes extensive intermolecular hydrogen bonding.
Hence `H_2O` exists as an associated molecule in which each O is tetrahedrally surrounded by four H atoms. Therefore. `H_2O` exists as a liquid at room temperature. On the orhter hand, `H_2S` does not exhibit hydrogen bonding `H_2S` exists as discrete molecules, which are held together by weak van der waals forces of attraction. Hence, `H_2S` is a gas.