The correct order of boiling points of hydrides of $15^{th}$ group elements is

Given below are two statements :
Statement $I$: Upon heating a borax bead dipped in cupric sulphate in a luminous flame,the colour of the bead becomes green.
Statement $II$: The green colour observed is due to the formation of copper$(I)$ metaborate.
In the light of the above statements,choose the most appropriate answer from the options given below :

The statement true for $N_3^-$ is

Which of the following hydrides of nitrogen is most acidic in nature?

When $NH_3$ is passed over heated $CuO$,what is it oxidized to?

Ammonia on reaction with hypochlorite anion,can form