A cubical metal block of edge 12 cm floats in mercry with one fifth of the height inside the mercury. Water poured till the surface of the block is just immersed in it. Find the height of the water column to be poured. Specific gravity of mercury =13.6.

Options

A. 1.25 cm
B. 2.5 cm
C. 5 cm
D. 7.5 cm

Answer

C

Explanation

Let h =height to of water column
then `rho_(w) gh+rho_(Hg)g(10-h)=rho_(Cu)g^(10)`
`rArr h+13.6(10-h)=73`
`rArr 63=12.6 h rArr h=5 cm `