# Question #cde77

Feb 25, 2016

(a) and (b) are both equivalent and are the correct answers.

#### Explanation:

First work out the number of moles of water in this 36 grams :

$n = \frac{m}{{M}_{r}}$

$= \frac{36}{1 + 1 + 16}$

$= 2 m o l$.

But 1 mole has $6.023 \times {10}^{23}$ particles.

Hence 2 moles will have $1.2046 \times {10}^{24}$ molecules.

This may also be written as $12.046 \times {10}^{23}$.

Thus the correct answer is both (a) and (b) as they are equivalent.