Question

How many molecules are present in 9g of water?

• A. 6.022$\times$ ${10}^{23}$
• B. 3.011$\times$ ${10}^{23}$
• C. 6.022$\times$ ${10}^{25}$
• D. 3.011$\times$ ${10}^{20}$

Answer 1

The correct option is B 3.011$\times$ ${10}^{23}$

Molecular mass of water = 18 g
$\therefore$ 18 g = 6.022 $\times$ ${10}^{23}$molecules of $H_{2}O$

$9g=\frac{6.022}{2}\times {10}^{23}moleculesof{H}_{2}O=3.011\times {10}^{23}moleculesof{H}_{2}O$