Nitrogen $(I)$ oxide $(N_2O)$ is produced by:

The correct sequence of decrease in the bond angle of the following hydrides is

Mercury $(II)$ chloride solution on reaction with gaseous ammonia forms:

White phosphorus is heated with concentrated $NaOH$ in $CO_2$ atmosphere to form a gas $A$ and compound $B$. When $A$ is bubbled into aqueous $CuSO_4$ solution,copper phosphide and $C$ are formed. $B$ and $C$ are respectively:

On reaction of $Lead$ $Sulphide$ with dilute nitric acid,which of the following is not formed?

The element which catches fire in air at $30^o\,C$ and is stored under water is