If 1 ml of water contains 20 drops. Then no. of molecules in a drop of water is

Options

A. `6.023xx10^(23)`
B. `1.376xx10^(26)`
C. `1.6673xx10^(21)`
D. `4.346xx10^(20)`

Answer

C

Explanation

1 mL of water = 1 g of water `(d_(H_(2)O)="1 g mL"^(-1))`
`therefore" 20 drops of "H_(2)O=1 g`
`therefore" 1 drop of "H_(2)O=(1)/(20)g=0.05g`
`=(0.05)/(18)"mole"=(0.05)/(18)xx6.022xx10^(23)" molecules"`
`=1.673xx10^(21)` molecules.