Consider two reactions:
$(I) \, Zn + \text{conc. } HNO_3 \text{ (hot)} \to Zn(NO_3)_2 + X + H_2O$
$(II) \, Zn + \text{dil. } HNO_3 \text{ (cold)} \to Zn(NO_3)_2 + Y + H_2O$
Compound $X$ and $Y$ are respectively:

Which of the following metals produces nitrous oxide $(N_2O)$ when reacted with dilute $HNO_3$?

Identify the correct orders from the following with respect to the property associated with:
$A$. $NH_3 > PH_3 > AsH_3 > SbH_3$ - Bond Angle
$B$. $NH_3 > PH_3 > AsH_3 > SbH_3$ - Basic Character
$C$. $PH_3 > AsH_3 > SbH_3 > NH_3$ - Thermal stability
$D$. $SbH_3 > NH_3 > AsH_3 > PH_3$ - Boiling point

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 :

Identify the incorrect statements about group $15$ elements :
$A$. Dinitrogen is a diatomic gas which acts like an inert gas at room temperature.
$B$. The common oxidation states of these elements are $-3, +3$ and $+5$.
$C$. Nitrogen has unique ability to form $p\pi-p\pi$ multiple bonds.
$D$. The stability of $+5$ oxidation states increases down the group.
$E$. Nitrogen shows a maximum covalency of $6$.
Choose the correct answer from the options given below.

On heating ammonium dichromate,the gas evolved is