liquid in a metallic pot boils quickly whose base is made black and rough than in a pot whose base is highly polished?

Its reason is being black its a good absorber and hence its will boil better. 
and if they are rough surfaces then also it will be work as a good absorbed and polished surface donot have that quality . 
HOPE IT CLEARS ..

A block body is good absorber of heat and light,and the black body will not release the heat energy gained easilyand rough body will have more surface area as compared to a polished body.