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A gun fires a lead bullet of temperature 300K into a wooden block. The bullet having melting temperature of 600 K penetrates into the block and melts down. If the total heat required for the process is 625 J, then the mass of the bullet is ___ grams. (Latent heat of fusion of lead = 2.5 × 10 4 JKg –1 and specific heat capacity of lead = 125 JKg –1 K –1 )

1. 20
2. 15
3. 10
4. 5

Correct answer: 10

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