Specific Heat | MCQs

Explanation

For a polyatomic gas, Cv is typically 3R, accounting for translational and rotational degrees of freedom.

This value can increase with temperature as vibrational modes become excited, contributing to the specific heat.

Explanation

For a diatomic gas (like O₂ or N₂), the ratio of specific heats 𝐶𝑝/𝐶𝑣 is approximately 1.4.

This ratio is also known as the adiabatic index (γ).

It is used in thermodynamic processes.

Explanation

To boil 1 liter of water from 15°C to 100°C, the energy required is:

Q = mcΔT

= 1 kg × 4.18 kJ/kg°C × (100°C - 15°C)

= 1 × 4.18 × 85

= 355 kJ

Explanation

Explanation

Specific heat capacity is the thermal energy transfer required per unit mass to increase the temperature of a substance by 1°C (or 1 K).

It is a measure of how much heat energy a substance can absorb or release per unit mass per unit temperature change.

Explanation

Heat capacity is the amount of heat energy required to change the temperature of a substance by a given amount.

It is calculated as the product of the mass of the substance and its specific heat capacity:

Heat Capacity = mass x specific heat capacity

Explanation

Let’s assume two cases:

• If $f = 3$ (monatomic gas), then:

  γ=3+2​/3=5/3​

• If $f = 5$ (diatomic gas), then:

  γ=5+2​/5=7/5​

Since the question asks for γ when degrees of freedom are 3 and 5, and γ = Cp/Cv, then:

• For f = 3 → γ = 5/3