Test: Heat - Grade 4 MCQ

The Kelvin scale's zero point is equivalent to 0°C, which is 273 K. This conversion is essential for scientific calculations that utilize the absolute temperature scale.

When a gas is heated in a closed container, its volume increases because the gas molecules move faster and push against the walls of the container more forcefully.

Birds puff up their feathers to trap air, which acts as an insulator, helping them retain body heat during cold weather. This adaptation is vital for their survival in colder climates.

During a chemical change, heat is either absorbed or released, depending on the nature of the reaction. This transfer of energy is crucial for processes such as combustion and respiration.

A thermos flask is designed to keep hot liquids hot and cold liquids cold by using a vacuum between its double walls, which minimizes heat transfer by conduction, convection, and radiation.

During evaporation, the temperature of the remaining liquid decreases because the molecules with the highest energy escape, leaving behind lower-energy molecules. This cooling effect is why sweat cools the body.

The process where a solid turns into a liquid because it absorbs heat is known as melting. For instance, ice melts into water at 0°C when it absorbs enough heat.

Copper is an excellent conductor of heat, which is why it is commonly used in cooking pots and electrical wiring. Good conductors allow heat to flow easily through them.

A good thermometric liquid, such as mercury or alcohol, expands evenly with temperature changes. This property allows for accurate temperature readings along a marked scale.

The freezing point of water is 0°C or 32°F. At this temperature, water transitions from a liquid to a solid state (ice) as it releases heat energy.

Combustion is a chemical reaction where a substance reacts with oxygen, producing heat and light. This process is crucial for energy production in various fuels.

Wool is a thermal insulator because it does not conduct heat well, making it ideal for keeping warmth in during cold weather. Insulators are essential for maintaining temperature in various applications.

Gaps are left between rail tracks to allow for thermal expansion. As temperatures rise, the metal expands; without gaps, the tracks could bend or buckle, leading to safety hazards.

Conformation is not a method of heat transfer. The three primary methods are conduction (through solids), convection (through fluids), and radiation (through space).

Heat energy increases the temperature of solids, liquids, and gases when it is applied. This effect is fundamental to understanding thermal energy and how it influences various states of matter.

Linear expansion occurs when a solid expands in length as it is heated. This principle is applied in various construction and engineering practices to accommodate changes in temperature.

Thermal expansion refers to the increase in size of materials when heated. Most materials expand in length, area, or volume as their temperature rises, which is essential in engineering and construction.

Water boils at 100°C, converting from a liquid state to steam (gas) by absorbing heat energy. This boiling point is crucial for various cooking and scientific applications.

A practical application of thermal expansion is heating a metal ball so it can fit through a ring. When heated, the ball expands, demonstrating how materials change size with temperature.

Condensation is the process where a gas turns into a liquid when it loses heat. For example, water vapor condenses into liquid water on a cold surface, forming droplets.