Use the value of the Avogadro constant $\left(6.02\times {10}^{23} {\mathrm{mol}}^{-1}\right)$ to calculate the total number of atoms in $7.10 \mathrm{g}$ of chlorine atoms. (${\mathrm{A}}_{\mathrm{r}}$ value: $\mathrm{Cl}=35.5$).

Use these ${\mathrm{A}}_{\mathrm{r}}$ values: $\mathrm{C}=12.0, \mathrm{O}=16.0$. 

Calculate the mass of $20$ moles of carbon dioxide, ${\mathrm{CO}}_2$.

Use these ${\mathrm{A}}_{\mathrm{r}}$ values: $\mathrm{C}=12.0, \mathrm{O}=16.0, \mathrm{Na}=23.0$.

Calculate the mass of $0.050$ moles of sodium carbonate, ${\mathrm{Na}}_2{\mathrm{CO}}_3$.

Use these ${\mathrm{A}}_{\mathrm{r}}$ values: $\mathrm{Fe}=55.8, \mathrm{H}=1.0, \mathrm{O}=16.0$.

Calculate the mass of $5.00$ moles of iron(II) hydroxide, $\mathrm{Fe}{\left(\mathrm{OH}\right)}_2$.

Sodium reacts with excess oxygen to form sodium peroxide, ${\mathrm{Na}}_2{\mathrm{O}}_2$.

$2\mathrm{Na}+{\mathrm{O}}_2\to {\mathrm{Na}}_2{\mathrm{O}}_2$

Calculate the maximum mass of sodium peroxide formed when $4.60 \mathrm{g}$ of sodium is burnt in excess oxygen. (${\mathrm{A}}_{\mathrm{r}}$ values: $\mathrm{Na}=23.0, \mathrm{O}=16.0$).

Tin(IV) oxide is reduced to tin by carbon. Carbon monoxide is also formed.

${\mathrm{SnO}}_2+2\mathrm{C}\to \mathrm{Sn}+2\mathrm{CO}$

Calculate the mass of carbon that exactly reacts with $14.0 \mathrm{g}$ of tin(IV) oxide. Give your answer to $3$ significant figures.

(${\mathrm{A}}_{\mathrm{r}}$ values: $\mathrm{C}=12.0, \mathrm{O}=16.0, \mathrm{Sn}=118.7$).