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

Options

A. 0.5 A/18
B. 0.05 A
C. 0.5 A
D. 0.05 A/18

Answer

D

Explanation

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 ) xx (1)/(20) = ( 0.05 A)/(18 ) ` molecules