An ice cube is floating in water above which a layer of a fighter oil is poured. As the ice melts completely, the level If water surface (or interface) and upper level of oil will

Options

A. rise and fall
B. fall and rise
C. not change and no change
D. not change and fall

Answer

A

Explanation

When ice melts into water its volume decrease. Hence, over all level should decrease.
Now suppose m is the mass of ice `(V_1)` is volume immersed in water and `(V_2)` the volume immersed in oil. Then in floating condition,
weight=upthrust
`:. mg=(V_1)(rho_w)g+(V_2)(rho_0)g`
`:. (V_1)=(m-(V_2)(rho_0))/(rho_w)`
`(m)/(rho_w)-(V_(2)(rho_0))/(rho_w)` ...(i)
When ice melts, m mass of ice converts into m mass of water. Volume of water so formed is
`V_(3)=(m)/(rho_(w))` ...(ii)
From Eqs. (i) and (ii) ,`V_(3)gtV_(1)`
`:.` Interface level will rise.