$1 \, L$ 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 $...... \times 10^{-3} \, mmol$.

Which of the following formulas is correctly represented according to Stock notation?

$(i)$ Calculate the total number of electrons present in one mole of methane.
$(ii)$ Find $(a)$ the total number and $(b)$ the total mass of neutrons in $7 \, mg$ of $^{14}C$. (Assume that mass of a neutron $= 1.675 \times 10^{-27} \, kg$).
$(iii)$ Find $(a)$ the total number and $(b)$ the total mass of protons in $34 \, mg$ of $NH_3$. Will the answer change if the temperature and pressure are changed?

When a standard solution of $NaOH$ is left in air for a few hours,

Mohr's salt is

Rearrange the following ($I$ to $IV$) in the order of increasing masses:
$(I)$ $0.5$ mole of $O_3$
$(II)$ $0.5 \, g$ atom of oxygen
$(III)$ $3.011 \times 10^{23}$ molecules of $O_2$
$(IV)$ $5.6 \, L$ of $CO_2$ at $STP$