Phosphine is prepared by the reaction of

Which of the following is a non-combustible hydride?

Arrange the hydrides of Group $15$ elements in the increasing order of their basic strength.

The $15^{th}$ group of the periodic table contains elements $N, P, As, Sb,$ and $Bi$. As we move from $N$ to $Bi$,how do the oxides with the general formula $E_2O_3$ behave?

Given below are the two statements: one is labeled as Assertion $(A)$ and the other is labeled as Reason $(R)$.
Assertion $(A)$: There is a considerable increase in covalent radius from $N$ to $P$. However,from $As$ to $Bi$,only a small increase in covalent radius is observed.
Reason $(R)$: Covalent and ionic radii in a particular oxidation state increase down the group.
In the light of the above statements,choose the most appropriate answer from the options given below:

At what temperature is white phosphorus heated to form $\beta$-black phosphorus (in $K$)?