Question

The volume of water molecule is (Take, density of water is ${10}^3$ kg $m^{-3}$ and Avogadro's number $=6\times {10}^{23}$ $mol{e}^{-1}$).

• 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)

$3\times {10}^{-29}{m}^3$

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