On complete combustion, $$0.492 \mathrm{~g}$$ of an organic compound gave $$0.792 \mathrm{~g}$$ of $$\mathrm{CO}_{2}$$. The % of carbon in the organic compound is ___________ (Nearest integer)

The strength of 50 volume solution of hydrogen peroxide is ______ $\mathrm{g} / \mathrm{L}$ (Nearest integer).

Some amount of dichloromethane $$\left(\mathrm{CH}_{2} \mathrm{Cl}_{2}\right)$$ is added to $$671.141 \mathrm{~mL}$$ of chloroform $$\left(\mathrm{CHCl}_{3}\right)$$ to prepare $$2.6 \times 10^{-3} \mathrm{M}$$ solution of $$\mathrm{CH}_{2} \mathrm{Cl}_{2}(\mathrm{DCM})$$. The concentration of $$\mathrm{DCM}$$ is ___________ ppm (by mass).

Given :

atomic mass : C = 12

H = 1

Cl = 35.5

density of $$\mathrm{CHCl}_{3}=1.49 \mathrm{~g} \mathrm{~cm}^{-3}$$

The volume of HCl, containing 73 g L$$^{-1}$$, required to completely neutralise NaOH obtained by reacting 0.69 g of metallic sodium with water, is __________ mL. (Nearest Integer)

(Given : molar masses of Na, Cl, O, H, are 23, 35.5, 16 and 1 g mol$$^{-1}$$ respectively.)