The density of Water at room temperature is 1.0 g/ml. How many molecules are there in a drop of water if its volume is 0.05 ml ?

Explanation

Volume of drop of water = 0.05 ml
Mass of a drop of water drop of water = Volume `xx` Density
= 0.05 ml `xx` 1.0 g/ml.
= 0.05 g
Molar mass of wif wataetre `(H_(2)O)` = 18 g
18 g of water = 1 mole
0.05 g of water = `1/18 xx` 0.05 = 0.0028 mol.
No. of molecules present in one mole of water = `6.023xx10^(23)`
No. of molecules present in 0.0028 mole of water `(60.23xx10^(23)xx0.0028)/1`
= `1.68xx10^(21)` water molecules.