Which element from following rapidly loses its luster in air and tarnishes?

A neon-dioxygen mixture contains $$64 \mathrm{~g} \mathrm{~O}_2$$ and $$160 \mathrm{~g} \mathrm{~Ne}$$. If the total pressure is $$25 \mathrm{~bar}$$, calculate the partial pressure of dioxygen.

Identify anionic sphere complex from following.

What is the number of moles of ethane obtained from $$2 n$$ moles of bromomethane using $$2 n$$ moles of sodium atoms in dry ether medium?