Chlorophyll extracted from the crushed green leaves was dissolved in water to make $$2 \mathrm{~L}$$ solution of Mg of concentration $$48\, \mathrm{ppm}$$. The number of atoms of $$\mathrm{Mg}$$ in this solution is $$x \times 10^{20}$$ atoms. The value of $$x$$ is ___________. (Nearest Integer)

(Given : Atomic mass of $$\mathrm{Mg}$$ is $$24 \mathrm{~g} \mathrm{~mol}^{-1} ; \mathrm{N}_{\mathrm{A}}=6.02 \times 10^{23} \mathrm{~mol}^{-1}$$ )

When 800 mL of 0.5 M nitric acid is heated in a beaker, its volume is reduced to half and 11.5 g of nitric acid is evaporated. The molarity of the remaining nitric acid solution is x $$\times$$ 10^$$-$$2 M. (Nearest integer)

(Molar mass of nitric acid is 63 g mol^$$-$$1)

56.0 L of nitrogen gas is mixed with excess hydrogen gas and it is found that 20 L of ammonia gas is produced. The volume of unused nitrogen gas is found to be _________ L.

A sample of 4.5 mg of an unknown monohydric alcohol, R-OH was added to methylmagnesium iodide. A gas is evolved and is collected and its volume measured to be 3.1 mL. The molecular weight of the unknown alcohol is __________ g/mol. [Nearest integer]