$16 \ g$ each of $H_2$,$He$,and $O_2$ are present in a container exerting $10 \ atm$ pressure at $T \ (K)$. The pressure in $atm$ exerted by $16 \ g$ each of $He$ and $O_2$ in the second container of same volume and temperature is

$1 \, L$ aqueous solution of $H_{2}SO_{4}$ contains $0.02 \, mmol$ $H_{2}SO_{4}$. $50 \%$ of this solution is diluted with deionized water to give $1 \, L$ solution $(A)$. In solution $(A)$,$0.01 \, mmol$ of $H_{2}SO_{4}$ are added. Total $mmol$ of $H_{2}SO_{4}$ in the final solution is $...... \times 10^{-3} \, mmol$.

What is the actual volume occupied by water molecules present in $20 \ cm^3$ of water (in $cm^3$)?

Which sample contains the largest number of atoms?

When iron sulfide is heated in air,a sulfur oxide $A$ is obtained. When $A$ is dissolved in water,it produces an acid. What is the basicity of this acid?

If one liter of air is repeatedly passed over heated copper and magnesium until no further reduction in volume occurs,the final volume of the air will be approximately ......... $mL$.