The number of water molecules in a drop of water weighing 0.018 g is

Options

A. `6.022xx10^(26)`
B. `6.022xx10^(23)`
C. `6.022xx10^(20)`
D. `9.9xx10^(22)`

Answer

C

Explanation

Weight of the water drop=0.018g
No. of moles of water in the drop=Mass of water/molar mass
=0.018/18=`10^(-3)` mole
No of water molecules present in 1 mole of water =`6.022xx10^(23)`
No. water molecules in one drop of water (`10^(-3)` mole)=`6.022xx10^(23)xx10^(-3)`
`=6.022xx10^(20)`