# Which of the following will cool quickly

$(a)\;\text{A polished metallic vessel filled with water at$100^{\circ}$C} \\(b)\;\text{Polished metallic vessel filled with oilat$100 ^{\circ}C$} \\(c)\;\text{A blackened metallic vessel filled with water at$100 ^{\circ}C$} \\(d)\;\text{A blackened metallic versel filled with oil at$100^{\circ}$C }$

A blackened metallic versel filled with oil at $100^{\circ}$ as black body radiates more heat
Hence d is the correct answer.