Question

The mass of a molecule of water is

• A. $3\times {10}^{-26}kg$
• B. $3\times {10}^{-25}kg$
• C. $1.5\times {10}^{-26}kg$
• D. $2.5\times {10}^{-26}kg$

Answer 1

The correct option is A $3\times {10}^{-26}kg$

$6.023\times {10}^{23}$ molecules have mass = $18$ g

$1$ molecule has mass =

$\frac{18}{6.023\times {10}^{23}}$ = $2.989\times {10}^{-23}g$ = $2.989\times {10}^{-26}kg$