The number of molecules in $16 \ g$ of methane is ...... $\times 10^{23}$.

The total number of gm-molecules of $SO_2Cl_2$ in $13.5 \ g$ of sulphuryl chloride is

Among the following,choose the ones with an equal number of atoms.
$A$. $212 \ g$ of $Na_2CO_3(s)$ [molar mass $= 106 \ g/mol$]
$B$. $248 \ g$ of $Na_2O(s)$ [molar mass $= 62 \ g/mol$]
$C$. $240 \ g$ of $NaOH(s)$ [molar mass $= 40 \ g/mol$]
$D$. $12 \ g$ of $H_2(g)$ [molar mass $= 2 \ g/mol$]
$E$. $220 \ g$ of $CO_2(g)$ [molar mass $= 44 \ g/mol$]
Choose the correct answer from the options given below.

The number of molecules in $16 \ g$ of methane is

What is the mass in grams of $0.25 \ mol$ water (in $g$)?

The Avogadro number is defined as ......