Which of the following correctly represents 360 g of water?
$\left(\mathrm{i}\right)$ $2$ moles of ${\mathrm{H}}_2\mathrm{O}$
$\left(\mathrm{ii}\right)$ $20$ moles of water
$\left(\mathrm{iii}\right)$ $6.022\times {10}^{23}$ molecules of water
$\left(\mathrm{iv}\right)$ $1.2044\times {10}^{25}$ molecules of water

If 1 gram of sulphur dioxide contains x molecules, how many molecules will be present in $1$ gram of oxygen? $(\mathrm{S}=32 \mathrm{u}; \mathrm{O}=16 \mathrm{u})$

The mass of one molecule of a substance is $4.65 \mathrm{x} {10}^{-23} \mathrm{g}$. What is its molecular mass? What could this substance be? 

Which contains more molecules, $10\mathrm{g}$ of sulphur dioxide $\left({\mathrm{SO}}_2\right)$ or $10\mathrm{g}$ of oxygen $\left({\mathrm{O}}_2\right)$? (Atomic masses: $\mathrm{S}=32\mathrm{u}$; $\mathrm{O}=16\mathrm{u}$)