Question

The volume of water molecule is
(Take, density of water is $10^3\, kg\, m^{-3}$ and avogadro’s number $= 6 \times 10^{23}$ mole$^{-1}$)

• A. $3 \times 10^{-28}\, m^3$
• B. $3 \times 10^{-29}\, m^3$
• C. $1.5 \times 10^{-28}\, m^3$
• D. $1.5 \times 10^{-29}\, m^3$

Answer 1

Answer: (B)

Molecular mass of water $= 18$
$\therefore \quad$ Number of molecules in $18\, g$
or$\quad0.018 \,kg$ of water $= 6 \times 10^{23}$
$\therefore \quad$ Mass of molecule of water $= \frac{0.018}{6\,\times\,10^{23}} = 3\times10^{-26}$
$\therefore \quad$ Volume of a water molecule
$= \frac{Mass}{Density} = \frac{3\,\times\,10^{-26}}{1000} = 3\times10^{-29}\,m^{3}$