Which of the following solids is not a molecular solid?

A solution containing 6.0 g of urea is isotonic with a solution containing 10 g of a non-electrolytic solute $$X$$. The molar mass of X (in g $$\mathrm{mol}^{-1}$$) is

$$x \%(w / V)$$ solution of urea is isotonic with $$4 \%$$ $$(w / V)$$ solution of a non-volatile solute of molar mass $$120 \mathrm{~g} \mathrm{~mol}^{-1}$$. The value of $$x$$ is

38.6 amperes of current is passed for 100 seconds through an aqueous $$\mathrm{CuSO}_4$$ solution using platinum electrodes. The mass of copper consumed from the solution and volume of gas liberated at STP are respectively (molar mass of $$\mathrm{Cu}=63.54 \mathrm{~g} \mathrm{~mol}^{-1}$$).