Which of the following property is true for the given sequence?

$$\mathrm{NH}_3>\mathrm{PH}_3>\mathrm{AsH}_3>\mathrm{SbH}_3>\mathrm{BiH}_3 \text { ? }$$

$$\mathrm{XeF}_6$$ on partial hydrolysis gives a compound $$X$$, which has square pyramidal geometry '$$X$$' is

A colourless, neutral, paramagnetic oxide of nitrogen '$$P$$' on oxidation gives reddish brown gas $$Q$$. $$Q$$ on cooling gives colourless gas $$R$$. $$R$$ on reaction with $$P$$ gives blue solid $$S$$. Identify $$P, Q, R, S$$ respectively