Arrange the following in the order of increasing mass (atomic mass: $O = 16, Cu = 63, N = 14$)
$I.$ one atom of oxygen
$II.$ one atom of nitrogen
$III.$ $1 \times 10^{-10}$ mole of oxygen
$IV.$ $1 \times 10^{-10}$ mole of copper

If the density of liquid water is $1.0 \, g \cdot cm^{-3}$ and the density of water vapor is $0.0006 \, g \cdot cm^{-3}$ at $100 \, ^\circ C$ and $1 \, atm$ pressure,then what is the volume occupied by water molecules in $1 \, L$ of steam at the same temperature in $cm^3$?

The total mass of a mixture containing $5.6 \ L$ of $H_2O$ and $1 \ g$ atom of $Zn$ is ............... $g$ $[H = 1, O = 16, Zn = 65.5]$

When $40 \, mL$ of $0.1 \, N \, HCl$ and $20 \, mL$ of $0.1 \, M \, H_2SO_4$ are mixed together,the normality of the mixture will be

$(i)$ Calculate the total number of electrons present in one mole of methane.
$(ii)$ Find $(a)$ the total number and $(b)$ the total mass of neutrons in $7 \, mg$ of $^{14}C$. (Assume that mass of a neutron $= 1.675 \times 10^{-27} \, kg$).
$(iii)$ Find $(a)$ the total number and $(b)$ the total mass of protons in $34 \, mg$ of $NH_3$. Will the answer change if the temperature and pressure are changed?

$0.45 \ g$ of an organic compound on combustion gives $0.792 \ g$ of $CO_2$ and $0.324 \ g$ of $H_2O$. In the Kjeldahl method,$0.24 \ g$ of the same compound yields ammonia,which is absorbed in $50 \ mL$ of $0.25 \ N \ H_2SO_4$. The excess acid requires $77.0 \ mL$ of $0.25 \ N \ NaOH$ for neutralization. Determine the empirical formula of the compound. (Atomic masses: $C = 12, H = 1, O = 16, N = 14, S = 32$)