A U tube contains water and methylated spirts separated by mercury columns in the two arms are in level with 10.0cm of water in one arm and 12.5 cm of spirit in the other. What is the relative density of spirit?

Explanation

for water column in one arm of U tube, `h_(1)=10.0cm, rho("density")=1g cm^(-3)`
for spirit column in other arm of U tube `h_(2)=12.5cm,rho=?`
As the mercury column in the two arms of U tube are in level, therefore pressure exerted by each is equal.
Hence, `h_(1)rho_(1)g=h_(2)g_(2)g` or `rho_(2)=h_(1)rho_(1)//h_(2)=10xx1//12.5=0.8gcm^(-3)`
therefore, relative density of spirit `=rho_(2)//rho_(1)=0.8//1=0.8`