A Cube made of material having density of `0.9 xx 10^(3) kg m^(-3)` floats between water and a liquid of density `0.7 xx 10^(3) kg//m^(3)` which is immiscible with water. What part of cube is immersed in water.

Options

A. `1/3`
B. `3/4`
C. `2/3`
D. `3/7`

Answer

C

Explanation

Let a be the side of the cube and x be the length dipping in water and (a -x) in the liquid
`thereforea^(3)xx0.9xx10^(3)g=a^(2)xx x xx 1000g+a^(2)(a-x)xx0.7xx10g`
`axx0.9=x+(a-x)0.7`
`0.3x=0.2a`
`x/a=2/3`
Thus correct choice is (c).