Thermal | MCQs

Explanation

• A change in physical appearance or state of a substance, such as a change in shape, size, color, or phase (solid, liquid, gas), is called a Physical Change.
  

The are examples of Physical Changes:

• Melting (ice cream, wax, chocolate, ice and change from solid to liquid)
• Phase changes (boiling, freezing, condensation)
• Crushing (chalk)
• Tearing (paper)
• Crumpling (aluminium foil)
• Stretching (rubber band)
• Mixing (sugar in water)
• Dissolving (sugar, salt in water)
• Moulding (clay, metals)
• Slicing (fruit)
• Forming of frost (from water vapors)
• Transition to a gas (change from liquid to gas)
• Change of durability (change in texture or strength)
• Changes to crystal form (change in crystal structure)

Explanation

A change in physical appearance or state of a substance, such as a change in shape, size, color, or phase (solid, liquid, gas), is called a Physical Change.

Explanation

• A release of gas is typically a sign of a chemical change, not a physical change.

The signs of physical change:

• Change that can be reversed
• The substance does not turn into a new substance

Explanation

• Thermal energy is the form of energy that is transferred from one body to another due to a difference in temperature, and is received from heat.
• It is the energy of motion of particles in a substance, such as atoms or molecules, and is often referred to as "heat energy".

Explanation

• In a solid, the particles are closely packed and have a fixed position.
• But they still have some freedom to vibrate or oscillate in place, due to their thermal energy.

Explanation

Matter changes state from:

• Solid to liquid (melting) when it gains energy
• Liquid to gas (vaporization) when it gains energy

This is because the particles need more energy to break free from their rigid structure in solids and move more freely in liquids, and even more energy to escape into the air as gases.

Explanation

• A thermal conductor is a material that allows heat energy to flow through it easily.
• Such as metals like copper, aluminum, and iron.

Explanation

The properties used to describe heat are:

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

Explanation

Moist air is lighter and less dense than dry air with the same temperature and pressure.

Explanation

The molecules in a solid are closely packed together and contain the least amount of kinetic energy.