Which of the following compounds is NOT obtained at any stage of Gabriel phthalimide synthesis?

The solution containing $18 \mathrm{~g} \mathrm{dm}^{-3}$ glucose (molar mass 180) in water and another containing $6 \mathrm{~g} \mathrm{dm}^{-3}$ of solute A in water boils at same temperature. What is molar mass of A ?

Which among following polymers is used to manufacture water pipes?

Identify the correct pair of molecule and the heteroatom present in it respectively from following: