If 1 mL of water contains 20 drops the number of molecules in a drop of water is (AFMC 2010)

Given, Volume of water ( 2 H O ) = 1 mL 1 mL volume of water contains 20 drops of water It is known that density of water is 1 and therefore 1mL of water=1 g of water 20 drops of 2 H O =1g 1 drop of 2 H O = 1 0.05 20 g g MOLE & EQUIVALENT CONCEPT 56 Mole of 2 H O = 0.05 18 mol Molecules of 2 H O = 23 0.05 6.023 10 18 molecules x x Molecules of 2 H O = 21 1.673 10 molecules x Thus, the correct answer is (a) 21 1.673 10 molecules x