Thermodynamics | MCQs

Explanation

The average translational kinetic energy of a molecule in an ideal gas is given by the formula:

E=3/2​kT

Where:

• $k = 1.38 times 10^{-23} , text{J/K}$ (Boltzmann constant)

• T=27∘C=300K (since 27°C + 273 = 300 K)

Now calculate:

E=3​/2×1.38×10^−23×300
E=3/2​×4.14×10^−21

6.21×10^−21 J

Explanation

Dynamic equilibrium is a state where the rates of forward and reverse reactions are equal, and the concentrations of reactants and products remain constant.

However, this equilibrium can be disturbed by external stresses such as:

• Changes in concentration
• Changes in temperature
• Changes in pressure
• Adding or removing reactants or products

Explanation

Bioenergetics is the process by which living organisms convert free energy into different forms.

Such as light energy to chemical energy in photosynthesis, or chemical energy from nutrients to kinetic energy in cellular respiration.

This conversion is essential for maintaining life and supporting various cellular activities.

Explanation

When water cools from 4°C to 0°C, ice crystals begin to form 

When water freezes, the water molecules form a lattice that increases the volume.

As a result, the density decreases

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ND22-1-2023

Explanation

• Heat is a form of energy that flows from a region of high temperature to a region of low temperature.
• This flow of energy occurs through the transfer of kinetic energy from particles in motion.

Explanation

• Freezing is the process by which a liquid changes to a solid.
• It is the reverse of melting, which is the process by which a solid changes to a liquid.

Explanation

• As temperature increases, the heat energy of a substance also increases.
• This is because temperature is a measure of the average kinetic energy of the particles in a substance, and as temperature increases, the particles gain kinetic energy and therefore heat energy.

Explanation

• James Prescott Joule established that the various forms of energy, mechanical, electrical and heat, are basically the same and can be changed from one form into another.
• He demonstrated that different forms of energy are interchangeable in his most famous experiment, published in 1845, using a paddle wheel to show that mechanical energy could be changed into thermal energy.

Explanation

• Heat is measured in Joules (J), which is the unit of energy.
• Heat is a form of energy transferred from one body to another due to a temperature difference.

Explanation

The properties used to describe heat are:

• Hot (high temperature)
• Energy (thermal energy)
• Cold (low temperature)