Calculate the number of oxygen atoms in $0.2 \mathrm{mole}$ of ${\mathrm{Na}}_2{\mathrm{CO}}_3.10{\mathrm{H}}_2\mathrm{O}$.

If the final answer is $\mathrm{x}\times {10}^{24}$, then give the value of $\mathrm{x}$.

Find the total number of nucleons present in $12 \mathrm{g}$ of ${}^{12}\mathrm{C}$ atoms.

Divide the answer by $1\times {10}^{24}$ and report the value in three significant figures.

(${\mathrm{N}}_{\mathrm{A}}=6.022\times {10}^{23}$)

Find (i) the total number of neutrons, and (ii) the total mass of neutrons in $7 \mathrm{mg}$ of ${}^{14}\mathrm{C}$. (Assume that the mass of a neutron $=$ mass of a hydrogen atom)

Calculate the volume in litres which occupied by $5.25 \mathrm{g}$ of nitrogen at $26°\mathrm{C}$ and $74.2 \mathrm{cm}$ of pressure.

Give the answer within two decimal places.