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

Nitric acid can be obtained from ammonia via the formation of the intermediate compounds:

In the following reaction,identify the nature of the product formed by the underlined atom upon complete hydrolysis at $R.T$.:
$H_4\underline{P}_2O_8 + H_2O \longrightarrow H_3PO_4 + H_2O_2$

The structure of white phosphorus is ........ .

Which one of the following is correct with respect to basic character?

Heating $(NH_4)_2Cr_2O_7$ liberates a gas. The same gas is obtained by: