On mixing two colourless gases,a deep brown colour is observed. The gases are

Give the preparation of Nitric acid $(HNO_3)$. Discuss its physical and chemical properties and state its uses.

Which of the following is not a cyclic oxyacid?

$P_4O_{10}$ is not used to dry $NH_3$ gas because

Account for the following observations:
$(A)$ $AlCl_3$ is a Lewis acid.
$(B)$ Though fluorine is more electronegative than chlorine yet $BF_3$ is a weaker Lewis acid than $BCl_3$.
$(C)$ $PbO_2$ is a stronger oxidizing agent than $SnO_2$.
$(D)$ The $+1$ oxidation state of thallium is more stable than its $+3$ state.

Give the preparation of ammonia. Discuss the physical and chemical properties of ammonia. Give the uses of ammonia.