Which of the following oxides of nitrogen is solid in nature at room temperature?

Which of the following is the correct order of stability of hydrides of Group $15$ elements?

The number of $P=O$ and $P-P$ bonds present in the oxoacid of phosphorus,prepared by treating red $P_4$ with alkali,are respectively:

Which one of the following combines with $Fe(II)$ ions to form a brown complex?

An orange solid $(X)$ on heating,gives a colourless gas $(Y)$ and a green residue $(Z).$ Gas $(Y)$ on treatment with $Mg,$ produces a white solid substance. Identify the white solid substance.

Which one of the following elements occurs free in nature?