Laplace pointed out that pressure variations in sound propagation are:
AAdiabatic, not isothermal
BIsothermal, not adiabatic
CIsometric, not isothermal
DIsotropic, not adiabatic
Answer & Solution
Correct answer: A. Adiabatic, not isothermal
1. Newton assumed the compressions happened slowly enough to stay at one temperature.
2. Laplace saw that sound compressions are far too fast for that.
3. There is little time for heat flow to maintain constant temperature.
4. These variations are therefore adiabatic and not isothermal.
_Source: NCERT Class XI Physics Part II, Ch 14 'Waves'_
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