Find the number of millimoles for $0.160 \ g$ sodium hydroxide.

$1 \text{ g}$ of $H_2$ contains the same number of molecules as in

The number of molecules in $4.25 \, g$ of ammonia is:

The mass of one hydrogen atom is of the order of

Which one of the following will have the largest number of atoms?
$(i)$ $1 \,g$ $Au_{(s)}$
$(ii)$ $1 \,g$ $Na_{(s)}$
$(iii)$ $1 \,g$ $Li_{(s)}$
$(iv)$ $1 \,g$ of $Cl_{2(g)}$

If $10^{20}$ grains are distributed in one second,then the time taken to distribute an Avogadro number of grains is ........ hours.