Online Test: Heat, Light and Sound | Class 7 Physics

Question 1 of 35

Which of the following is the correct definition of temperature?

Total energy of all particles

Average kinetic energy of particles

The flow of energy from hot to cold

The mass of an object times its speed

Explanation: Temperature measures the average motion of particles, not total energy.

Question 2 of 35

Heat is measured in which unit?

Degrees Celsius (°C)

Kelvin (K)

Joules (J)

Meters (m)

Explanation: Heat is a form of energy, so its unit is Joule. Temperature is measured in °C or K.

Question 3 of 35

A large lake at 25°C and a small cup of tea at 85°C. Which has more heat?

The cup of tea

The lake

Both have same heat

Cannot be determined

Explanation: The lake has huge mass, so even at lower temperature, its total heat is much larger.

Question 4 of 35

Heat flows from an object with …

lower temperature to higher temperature

higher temperature to lower temperature

higher mass to lower mass

lower mass to higher mass

Explanation: Heat always moves from hotter to colder objects until they reach the same temperature.

Question 5 of 35

Two metal blocks are made of the same material. Block X has mass 500 g at 100°C. Block Y has mass 100 g at 100°C. Which statement is true?

Both have same heat

Block X has more heat

Block Y has more heat

Both have same temperature but heat cannot be compared

Explanation: Same temperature and same material means each gram has same average energy. More grams = more total heat.

Question 6 of 35

What is the purpose of the kink in a clinical thermometer?

To make it look different

To prevent mercury from flowing back quickly

To allow mercury to expand faster

To break if overheated

Explanation: The kink traps the mercury column so you can remove the thermometer and read it slowly.

Question 7 of 35

What is the normal human body temperature in Fahrenheit?

37°F

98.6°F

100°F

212°F

Explanation: 37°C × 9/5 + 32 = 66.6 + 32 = 98.6°F

Question 8 of 35

Which thermometer can be used to measure the temperature of boiling water?

Clinical thermometer only

Laboratory thermometer only

Both

Neither

Explanation: Boiling water is 100°C. Clinical thermometer range ends at 42°C, so it would break.

Question 9 of 35

Convert 50°C to Fahrenheit.

90°F

100°F

122°F

82°F

Explanation: (50 × 9/5) + 32 = 90 + 32 = 122°F

Question 10 of 35

While using a laboratory thermometer, the bulb should …

touch the bottom of the container

be completely immersed but not touch bottom/sides

be partly above the liquid

be held by hand inside the liquid

Explanation: Touching the bottom or sides measures container temperature, not the liquid. Complete immersion ensures accurate liquid temperature.

Question 11 of 35

Which method of heat transfer can occur in a vacuum (empty space)?

Conduction only

Convection only

Radiation only

All three

Explanation: Radiation uses electromagnetic waves and does not need particles. Conduction and convection require a medium.

Question 12 of 35

When water is heated in a kettle, the water at the bottom rises to the top. This is an example of …

Conduction

Convection

Radiation

Expansion

Explanation: Hot water becomes less dense and rises; cool water sinks. This is a convection current.

Question 13 of 35

Which of the following is the best conductor of heat?

Wood

Plastic

Copper

Air

Explanation: Copper is a metal. Metals are excellent conductors. Wood, plastic, and air are insulators.

Question 14 of 35

Why are shiny foil blankets given to athletes after a race?

To keep them cool

To reflect their body heat back

To absorb sweat

To weigh them down

Explanation: Shiny surfaces reflect radiation. The blanket reflects the athlete's body heat back, keeping them warm.

Question 15 of 35

Which of these is NOT an example of convection?

Hot air rising from a radiator

Sea breeze

A metal rod getting hot at one end

Boiling water

Explanation: A metal rod getting hot is conduction. The other three involve fluid movement (air or water).

Question 16 of 35

Which of the following is the BEST conductor of heat?

Wood

Plastic

Silver

Air

Explanation: Silver is the best conductor of heat among all metals. Wood, plastic, and air are insulators.

Question 17 of 35

Why are frying pans usually made of metal?

Metal is cheaper

Metal conducts heat well

Metal looks attractive

Metal is lightweight

Explanation: The pan needs to transfer heat from the stove to the food quickly and evenly. Conductors like metal do this well.

Question 18 of 35

Which material is commonly used as an insulator in the handles of cooking utensils?

Copper

Aluminum

Wood

Iron

Explanation: Wood is a poor conductor (insulator) and prevents heat from reaching your hand.

Question 19 of 35

Why does a metal spoon feel colder than a wooden spoon at room temperature?

Metal is actually colder

Metal conducts heat away from your hand faster

Wood stores more heat

Wood is warmer than metal

Explanation: Both are at room temperature. Metal conducts heat away from your hand quickly, making it feel cold.

Question 20 of 35

Which of the following is an example of a heat insulator?

Copper wire

Aluminum foil

Woolen sweater

Iron nail

Explanation: Wool traps air, which is an insulator. The others are metals (conductors).

Question 21 of 35

During the day, wind blows from the sea towards the land. This is called …

Land breeze

Sea breeze

Monsoon wind

Cyclone

Explanation: Daytime = land warmer = sea breeze (sea to land).

Question 22 of 35

Which surface heats up faster under the Sun?

Land

Water

Both heat at same rate

Depends on color

Explanation: Land (sand, soil) has lower specific heat capacity than water, so it heats faster.

Question 23 of 35

Land breeze occurs during the …

Daytime

Nighttime

Both day and night

Only in winter

Explanation: At night, land cools faster than sea, so wind blows from land to sea (land breeze).

Question 24 of 35

What causes sea breeze and land breeze?

Rotation of Earth

Unequal heating of land and water

Gravitational pull of Moon

Magnetic field of Earth

Explanation: Temperature difference between land and water creates pressure differences, causing convection currents.

Question 25 of 35

At midnight, you are standing on a beach. The wind is likely blowing from …

Sea to land

Land to sea

Upward from the sand

No wind at all

Explanation: Midnight = land is cooler than sea = land breeze (land to sea).

Question 26 of 35

When a substance is heated, its particles …

move slower and come closer

move faster and move apart

stop moving completely

change their color

Explanation: Heat increases particle kinetic energy, causing them to move more and push apart → expansion.

Question 27 of 35

Which state of matter expands the MOST when heated?

Solid

Liquid

Gas

All expand equally

Explanation: Gas particles are already far apart and free to move; heating makes them move much farther apart.

Question 28 of 35

Gaps left between railway tracks are called …

Expansion joints

Welding points

Track separators

Safety gaps

Explanation: Expansion joints allow space for rails to expand on hot days without buckling.

Question 29 of 35

A metal lid on a glass jar is stuck. Which method will help open it?

Put it in the freezer

Run hot water over the lid

Hit it with a hammer

Leave it in the sun

Explanation: Metal expands more than glass when heated, making the lid slightly larger and easier to remove.

Question 30 of 35

Water freezes at 0°C. When water turns into ice, it …

expands

contracts

stays the same volume

turns into gas

Explanation: Water has anomalous expansion — it expands by about 9% when freezing.

Question 31 of 35

What does "latent" mean in the term "latent heat"?

Large

Hidden

Liquid

Hot

Explanation: Latent comes from Latin meaning "hidden" — the heat does not show as temperature change.

Question 32 of 35

During melting of ice at 0°C, the temperature of the ice-water mixture …

increases steadily

decreases steadily

remains constant

first increases then decreases

Explanation: All heat added during melting is used as latent heat to break bonds, not to raise temperature.

Question 33 of 35

The latent heat of vaporization is larger than the latent heat of fusion because …

liquids are heavier

gases are invisible

breaking all bonds (liquid→gas) needs more energy than loosening bonds (solid→liquid)

boiling happens at higher temperature

Explanation: Vaporization requires completely separating particles; fusion only requires loosening them.

Question 34 of 35

When water freezes into ice, it …

absorbs latent heat

releases latent heat

neither absorbs nor releases

changes temperature

Explanation: Freezing is the reverse of melting. Heat that was absorbed during melting is released during freezing.

Question 35 of 35

Why does sweating cool your body?

Sweat is cold when it comes out

Sweat absorbs latent heat from skin to evaporate

Sweat blocks heat from entering

Sweat reflects sunlight

Explanation: Evaporation requires latent heat, which is taken from your skin, cooling you down.

Online Test — Heat, Light and Sound