$$1 \mathrm{~g}$$ of a carbonate $$\left(\mathrm{M}_{2} \mathrm{CO}_{3}\right)$$ on treatment with excess $$\mathrm{HCl}$$ produces $$0.01 \mathrm{~mol}$$ of $$\mathrm{CO}_{2}$$. The molar mass of $$\mathrm{M}_{2} \mathrm{CO}_{3}$$ is __________ $$\mathrm{g} ~\mathrm{mol}^{-1}$$. (Nearest integer)

An organic compound gives $$0.220 \mathrm{~g}$$ of $$\mathrm{CO}_{2}$$ and $$0.126 \mathrm{~g}$$ of $$\mathrm{H}_{2} \mathrm{O}$$ on complete combustion. If the $$\%$$ of carbon is 24 then the $$\%$$ of hydrogen is __________ $$\times 10^{-1}$$. ( Nearest integer)

$$20 \mathrm{~mL}$$ of calcium hydroxide was consumed when it was reacted with $$10 \mathrm{~mL}$$ of unknown solution of $$\mathrm{H}_{2} \mathrm{SO}_{4}$$. Also $$20 \mathrm{~mL}$$ standard solution of $$0.5 ~\mathrm{M} ~\mathrm{HCl}$$ containing 2 drops of phenolphthalein was titrated with calcium hydroxide, the mixture showed pink colour when burette displayed the value of $$35.5 \mathrm{~mL}$$ whereas the burette showed $$25.5 \mathrm{~mL}$$ initially. The concentration of $$\mathrm{H}_{2} \mathrm{SO}_{4}$$ is _____________ M. (Nearest integer)