Which pair of metals does not dissolve in nitric acid?

Which oxide is least acidic?

Which of the following is one of the products obtained when calcined phosphate rock is reduced with coke and sand in an electric furnace at $1773 \ K$?

Given below are two statements:
Statement-$I$: Element '$X$' and '$Y$' are the most and least electronegative elements, respectively, among $N, As, Sb$ and $P$. The nature of the oxides $X_{2}O_{3}$ and $Y_{2}O_{3}$ is acidic and amphoteric, respectively.
Statement-$II$: $BCl_{3}$ is covalent in nature and gets hydrolysed in water. It produces $[B(OH)_{4}]^{-}$ and $HCl$ in aqueous medium.

What are the products formed when ammonia reacts with excess chlorine?

Litharge is chemically