Number of water molecules in the drop of water, if 1 mL of water has 20 drops and A is Avogadro's number, is

Question

Number of water molecules in the drop of water, if 1 mL of water has 20 drops and A is Avogadro's number, is (A) 0.5 A / 18 (B) 0.05 A (C) 0.5 A (D) 0.05 A / 18

Tardigrade Admin · Accepted Answer

1 mole i.e. 18 g contains =A molecules For water, density =1 g / mL Thus 18 g ≡ 18 mL 1 mL (or 20 drop) will contain =(A/18) molecules 1 drop will contain =(A/18) × (1/20)=(0.05 A/18) molecules

Q. Number of water molecules in the drop of water, if $1 m L$ of water has $20$ drops and $A$ is Avogadro's number, is

$0.5 A /18$

$0.05 A$

$0.5 A$

$0.05 A /18$

1 mole i.e. $18 g$ contains $= A$ molecules

For water, density $= 1 g / m L$

Thus $18 g \equiv 18 m L$

$1 m L$ (or 20 drop) will contain $= \frac{A}{18}$ molecules

$1$ drop will contain $= \frac{A}{18} \times \frac{1}{20} = \frac{0.05 A}{18}$ molecules

Q. Number of water molecules in the drop of water, if 1mL of water has 20 drops and A is Avogadro's number, is

0.5A/18

0.05A

0.5A

0.05A/18