A cube of side `10cm` is filled with ice of density `0.9//c.c` Thickness of the walls of the cube is `1mm` and thermal conductivity of the material of the cube is steam bath maintained at a placed in steam bath maintained at a temperature of `100^(@)C` the time in which ice completely melts is `(L_(ice)=80cal//gm)` .

Options

A. `6 sec`
B. `12 sec`
C. `24 sec`
D. `48 sec`

Answer

B

Explanation

`mL_(ice)=(KA(Deltatheta)t)/(d)`
`rho_(ice)(a)^(3)L_(ice)=(K(6a^(2))(Deltatheta)t)/(d)`
here, a d are side and thickness of cube Heat conducts through six faces .