Which from following polymers is used as wool substitute?

Which from following compounds does NOT contain nitrogen in it?

A container contains $4 \mathrm{~g} \mathrm{H}_2, 4 \mathrm{~g} \mathrm{He}$ and certain amount of 'Ne' at a certain temperature. What is the mass of 'Ne' required so that the partial pressure exerted by 'Ne' is equal to the partial pressure of He ?

Find the EAN of Zn in $\left[\mathrm{Zn}\left(\mathrm{NH}_3\right)_4\right]^{2+}$ ?