Question

The number of water molecules present in a drop of water (volume 0.0018 mL) at room temperature is :

(A) $6.023 \times 10^{19}$

(B) $1.084 \times 10^{19}$

(C) $4.84 \times 10^{17}$

(D) $6.023 \times 10^{23}$

Answer 1

ANSWER : Here, The room temperature will be $6.023 \times 10^{19}$

So, The correct answer of this question will be option (A).

Explanation :

Mass of one drop of water $=$ vol. $\times$ density $=0.0018 g$

Number of water molecules in $18 g$ water $(1 mole )=6.022 \times 10^{23}$

Number of water molecules in $0.0018 g$ water

$=\frac{6.022 \times 10^{23}}{18} \times 0.0018=6.022 \times 10^{19}$