The height of the mercury column in a barometer at a place is 75 cm. If a liquid of unknown density is used the height of the liquid column is 150 cm, find its density.

Explanation

Since the atmospheric pressure is the same in both the cases,
`h_(1)d_(1)=h_(2)d_(2)`
The height of liquid column is double the height of the mercury column.
`therefore` its density should be half the density of mercury.
`therefore dl=(13.6)/(2)=6.8 g cm^(-3)`