Question

The mass of one molecule of water is approximately:

• A. $3\times {10}^{-23}g$
• B. $18g$
• C. $1.5\times {10}^{-23}g$
• D. $4.5\times {10}^{-23}g$

Answer 1

The correct option is A $3\times {10}^{-23}g$

Mass of $6.02\times {10}^{23}$ molecules of $H_{2}O=18g$

$\therefore$ Mass of 1 molecule of $H_{2}O$ $=\frac{18}{6.023\times {10}^{23}}=3\times {10}^{-23}g$