(a) State how many atoms there are in:

(i) A mole of helium gas (a molecule of helium has one atom)

(a) State how many atoms there are in:

(ii) A mole of chlorine gas (a molecule of chlorine has two atoms)

 State how many atoms there are in one kilo moles of neon gas (a molecule of neon has one atom).

A container holds four moles of carbon dioxide of molecular formula ${\mathrm{CO}}_2$ Calculate the number of carbon dioxide molecules there are in the container.

A container holds four moles of carbon dioxide of molecular formula ${\mathrm{CO}}_2$. Calculate the number of carbon atoms there are in the container.

(b) A container holds four moles of carbon dioxide of molecular formula ${\mathrm{CO}}_2$ Calculate:

(iii) The number of oxygen atoms there are in the container.

A bar of gold-$197$ has a mass of $1.0 \mathrm{kg}$. Calculate the mass of one gold atom in $\mathrm{kg}$.

A bar of gold-$197$ has a mass of $1.0 \mathrm{kg}$. Calculate the number of gold atoms in the bar.

A bar of gold-$197$ has a mass of $1.0 \mathrm{kg}$. Calculate:

(c) The number of moles of gold in the bar. (An atom of gold contains 197 nucleons and has a mass of 197 u.)