Science
MediumQ. No. gases-have-two-types-of-specific-heats-what-are-they
Gases have two types of specific heats. What are they?
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ACv and Cp
BCs and Ck
CCf and Cb
DCh and Cl
Correct Answer: Cv and CpYour Answer: A
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Gases are unique in that they have two distinct specific heats, unlike solids and liquids which have only one. Option A (Cv and Cp) is CORRECT — gases have two specific heats: (1) Specific heat at constant volume (Cv) — the heat required to raise the temperature of 1 mole of gas by 1°C while keeping the volume constant. At constant volume, no work is done against external pressure. (2) Specific heat at constant pressure (Cp) — the heat required to raise the temperature of 1 mole of gas by 1°C while keeping the pressure constant. At constant pressure, the gas expands and does work against external pressure, so more heat is needed. Therefore Cp > Cv always. The ratio γ = Cp/Cv is called the adiabatic index or heat capacity ratio and is approximately 1.4 for diatomic gases like air (N₂, O₂). Option B (Cs and Ck) is incorrect — these are not standard symbols for specific heats of gases in thermodynamics. Option C (Cf and Cb) is incorrect — no such standard thermodynamic quantities exist. Option D (Ch and Cl) is incorrect — these have no standard meaning in thermodynamics related to specific heats of gases. For exams: Cp - Cv = R (Mayer's relation), where R is the universal gas constant = 8.314 J/mol/K.
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Common questions and clear answers for this topic.
Heat is a form of energy that transfers between objects or systems due to a temperature difference, moving from a hotter body to a cooler one until thermal equilibrium is reached.
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