Which of the following oxides is neutral?

The correct decreasing order of basicity of hydrides of group-$15$ elements is

Consider the following reaction and select the incorrect statement about gas $(P)$:
$Zn + HNO_3 (\text{Dilute}) \to Zn(NO_3)_2 + P \uparrow $

The element that does $NOT$ exhibit allotropy is$-$

Phosphine is obtained by the reaction of which of the following?

In which of the following arrangements,the sequence is not strictly according to the property written against it?