The density of a pure liquid (molecular mass =80) is 1.5 gm/ml. if 4 ml of liquid contains 60 drops then the number of molecules per drops of liquid is give by : [Given `N_(A)=6xx10^(23)`]

Options

A. `7.5xx10^(20)`
B. `1.33 xx10^(21)`
C. `4xx10^(23)`
D. `2xx10^(22)`

Answer

A

Explanation

`d=M/V`
M=4x 1.5 =6gm
6 gm have 60 drops
1 drop will have 0.1 gm
`n=0.1/8xx6xx10^(23) =7.5xx10^(20)` molecules