Learn › Homi Bhabha Class 6 · Physics ›
Heat › Thermal Expansion
Thermal Expansion — Homi Bhabha Class 6 Physics MCQs with Solutions
Free Homi Bhabha Class 6 Physics Thermal Expansion MCQs with step-by-step solutions (10 questions). Part of Heat. Practise online on Prepizo — no login needed.
▶ Practise Thermal Expansion online (free)
Questions with solutions
Q1 — Thermal Expansion · easy · theory
Most substances, when they are heated, usually:
A. contract (shrink in size)
B. disappear
C. become colder
D. expand (increase in size) ✓ Correct
Solution: On heating, the tiny particles of most substances move a little apart, so the substance expands and takes up more space.
Q2 — Thermal Expansion · easy · theory
When a substance is cooled, it usually:
A. expands
B. starts glowing
C. contracts (shrinks) ✓ Correct
D. becomes heavier
Solution: On cooling, the particles come closer together, so the substance contracts, or shrinks a little in size.
Q3 — Thermal Expansion · easy · theory
Small gaps are left between two railway tracks so that:
A. the tracks have room to expand in hot weather ✓ Correct
B. rain water can drain away
C. trains can slow down
D. the sound of the train is reduced
Solution: In hot weather the metal tracks expand and get longer. The gaps give them room to expand without bending or breaking.
Q4 — Thermal Expansion · easy · theory
The tight metal lid of a glass jar becomes easier to open after running it under hot water because the metal lid:
A. becomes heavier
B. expands ✓ Correct
C. melts
D. contracts
Solution: The hot water heats the metal lid, and the metal expands more than the glass. The slightly bigger lid then turns easily.
Q5 — Thermal Expansion · medium · theory
For the same rise in temperature, which of these expands the most?
A. solids
B. they all expand equally
C. liquids
D. gases ✓ Correct
Solution: Gases expand the most on heating, liquids expand less, and solids expand the least for the same rise in temperature.
Q6 — Thermal Expansion · medium · theory
Electric and telephone wires hang more loosely (sag) in summer because they:
A. expand in the heat ✓ Correct
B. carry more current
C. become wet
D. contract in the heat
Solution: In the summer heat the metal wires expand and become a little longer, so they sag between the poles.
Q7 — Thermal Expansion · medium · theory
A metal ball just fits through a metal ring. After the ball is heated strongly, it:
A. becomes lighter and floats
B. melts into the ring
C. does not pass through because it has expanded ✓ Correct
D. passes through the ring even more easily
Solution: Heating makes the ball expand and grow slightly bigger, so it can no longer pass through the same ring.
Q8 — Thermal Expansion · medium · theory
Bridges are built with small gaps or rollers at their ends mainly so that:
A. the bridge can expand and contract without cracking ✓ Correct
B. cars are forced to slow down
C. rain water can pass through
D. the bridge looks more beautiful
Solution: A bridge expands in heat and contracts in cold. The gaps and rollers let it change length safely without cracking.
Q9 — Thermal Expansion · hard · theory
A glass bottle is filled to the brim with water and left in the hot sun. Some water spills out because:
A. the water expands more than the glass ✓ Correct
B. water is created by the sunlight
C. the bottle shrinks in the sun
D. the glass expands more than the water
Solution: Both the glass and the water expand on heating, but water expands much more than glass. The extra water has nowhere to go, so it spills out.
Q10 — Thermal Expansion · hard · theory
On a very hot day an iron gate becomes harder to close than on a cold day. This is because the iron has:
A. become lighter
B. contracted
C. rusted
D. expanded ✓ Correct
Solution: The heat makes the iron gate expand and become slightly larger, so it no longer fits its frame easily and is harder to close.