Question

A vessel contains oil (density `=0.8gm//cm^3`) over mercury (density `=13.6gm cm^3`). A homogeneous sphere floats with half its volume immersed in mercury and the other half in oil. The density of the material of the sphere in `gm//cm^3` is
A. (a) 3.3
B. (b) 6.4
C. (c) 7.2
D. (d) 12.8

Answer 1

Correct Answer - C
Weight of sphere
=Upthrust due to Hg+Upthrust due to oil
`Vdg=V/2dH_gg+V/2d_(oil)xxg`
`implies d=(d_(Hg)+d_(oil))/(2)=(13.6+0.8)/(2)=7.2g//cm^3`