Physics
Three substances A, B and C of same mass are present at their respective melting points. On heating, if they melt completely in 5 minutes, 7 minutes and 3 minutes respectively, then which substance has the highest specific latent heat?
(Assume heat is absorbed at the same rate)
- Substance A
- Substance B
- Substance C
- All the substances have same specific latent heat
Answer
Substance B
Reason — When substances are at their melting point, the heat supplied is used for melting and is given by Q = mL, where L is the specific latent heat.
Since the masses are the same and heat is absorbed at the same rate, the substance that takes the longest time to melt requires more heat and therefore has a higher specific latent heat.
Among A (5 min), B (7 min), and C (3 min), substance B takes the longest time.
Hence, substance B has the highest specific latent heat.
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(c) The lid of a calorimeter minimises heat loss by …………… [convection / radiation].
(d) Quality of sound depends on its …………… [amplitude / waveform].
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(f) …………… radiation deviates minimum in a magnetic field [Alpha / Beta].