Compound $$\mathrm{P}$$ is neutral, $$\mathrm{Q}$$ gives effervescence with $$\mathrm{NaHCO}_{3}$$ while $$\mathrm{R}$$ reacts with Hinsbergs reagent to give solid soluble in $$\mathrm{NaOH}$$. Compound $$\mathrm{P}$$ is

Match List I with List II

Choose the correct answer from the options given below:

A compound is formed by two elements $$\mathrm{X}$$ and $$\mathrm{Y}$$. The element $$\mathrm{Y}$$ forms cubic close packed arrangement and those of element $$\mathrm{X}$$ occupy one third of the tetrahedral voids. What is the formula of the compound?

Strong reducing and oxidizing agents among the following, respectively, are :