A gun fires a lead bullet of temperature 300 K into a wooden block. The bullet having melting temperature of 600 K penetrates into the block and…

A gun fires a lead bullet of temperature $\displaystyle 300$ K into a wooden block. The bullet having melting temperature of $\displaystyle 600$ K penetrates into the block and melts down. If the total heat required for the process is $\displaystyle 625$ J , then the mass of the bullet is $\displaystyle \_\_\_\_$ grams. (Latent heat of fusion of lead $\displaystyle =2.5 \times 10^4 \mathrm{JKg}^{-1}$ and specific heat capacity of lead $\displaystyle =125 \mathrm{JKg}^{-1}$ $\displaystyle \mathrm{K}^{-1}$ )