Question

Number of molecules in one litre of water is close to:

• A. $55.5\times 6.023\times 10^{23}$
• B. $18\times 6.023\times 10^{23}$
• C. $18÷22.4\times 10^{23}$
• D. $1.8\times 10^{23}$

Answer 1

Answer: (A)

$1L{H}_{2}O=1000cc=1000g$
$\therefore 18g$ of $H_{2}O=6.023\times 10^{23}$ molecules
$\therefore 1000g$ of $H_{2}O=\frac{6.023\times 10^{23}\times 1000}{18}$
$=6.023\times 10^{23}\times 55.5$ molecules