Grade 7 · Science · Unit 7 of 9
Heat & Particles
Heat, motion and changing state
What your child practises
Heat as energy linked to particle motion, temperature, expansion and contraction, changes of state, and the ways heat is generated (friction, electricity, burning, chemical reactions and the Sun).
Saskatchewan Curriculum outcome: HT7.2 · states of matter and the effect of heat on the particle model
Sample questions
A taste of this unit. In the app, questions change every time and get easier or harder to match your child.
Question 1
A pot of water is heated from 15 °C to 65 °C. By how many degrees did its temperature rise?
answer box°C
Show answer
50 °C
Hint: Subtract: 65 − 15.
Question 2
Temperature is a measure of…
- how fast the particles are moving, on average
- how big the particles are
- how many particles there are
- how much space the substance fills
Show answer
how fast the particles are moving, on average
Hint: A hotter object has particles with more motion energy on average.
Question 3
Gas particles in a sealed rigid container are heated. What happens to the pressure inside?
- It stays the same
- The particles disappear
- It decreases because the particles slow down
- It increases because the particles hit the walls more often and harder
Show answer
It increases because the particles hit the walls more often and harder
Hint: Faster particles hit the walls with more force.
Question 4
How does a liquid thermometer work?
- The liquid disappears when cooled
- The liquid turns into a solid
- The tube grows when heated
- The liquid expands when heated and rises in the tube
Show answer
The liquid expands when heated and rises in the tube
Hint: A warmer liquid takes up more space, so it climbs higher.
Question 5
At 400 °C, what state is mercury?
mercury Melting point Boiling point −39 °C 357 °C - liquid
- gas
- solid
Show answer
gas
Hint: Below the melting point it is a solid. Between the melting and boiling points it is a liquid. Above the boiling point it is a gas.
Question 6
As a solid melts, its particles…
- stop vibrating
- become different particles
- lose all their energy
- gain energy and move more freely
Show answer
gain energy and move more freely
Hint: The particles still stay close but are no longer fixed in place.