Part 1 of 2

Squeeze a gas

identify / state

Try it yourself

identify: name or select. state: give a concise answer.

A sealed gas syringe holds a fixed amount of air. Disc weights are added to its plunger one at a time, and the water bath around it stays at 20 °C. Use the results to choose the statement that describes what happened to the volume of the air. Then state what was kept the same.

Weights on the plunger	Volume / cm³
0 (start)	50
1	33
2	25
3	20

Choose one answera.The volume decreased by the same amount with each weight.b.The volume decreased with each weight, but by less each time.c.The volume stayed the same, because no air could get out.d.The volume increased, because the air was pushed harder.

What was kept the same while the weights were added?

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Scope and sources

Cambridge IGCSE Chemistry 0620 · 2026–2028 v2 · Original learning materials.

The effects of pressure and temperature on the volume of a gas (1.1.4) and their explanation with kinetic particle theory (Supplement 1.1.6), with a recap of gas particles from 1.1.2. The experiment uses one ideal sealed sample of air; gas-law equations and numerical gas calculations are not part of this module.

Apparatus, amounts and times in the experiment are illustrative. Real practical work follows a teacher-approved safety method.

Official Cambridge syllabus