CIE iGCSE Co-Ordinated Science C12.1 Experimental design Exam Style Questions Paper 2

Question

Sea water is heated in the apparatus shown.

Which row describes changes at positions X and Y?

▶️ Answer/Explanation

This is a simple distillation setup for purifying water from sea water: at position X (the heated flask), water evaporates (changes from liquid to gas), while at position Y (the condenser/collection flask), the water vapour condenses (changes from gas to liquid).
The salt remains behind in the flask because it does not evaporate; only pure water vapour travels to the collection vessel — matching row C which shows evaporation at X and condensation at Y.
✅ Answer: (C)

Question

An experiment is assembled to measure the rate of reaction between limestone and hydrochloric acid.

In the experiment a gas is released. The volume of gas produced is measured every five seconds.

Which piece of apparatus cannot be used to measure the volume of gas?

A. burette
B. measuring cylinder
C. pipette
D. gas syringe

▶️ Answer/Explanation

A pipette is designed to deliver a precise, fixed volume of liquid and has a very narrow tip — it cannot collect or measure the volume of a gas produced in a reaction.
A gas syringe directly collects gas, a measuring cylinder (inverted over water) can collect gas by displacement, and a burette can also be used inverted — but a pipette has no mechanism to trap or measure gas volumes.
✅ Answer: (C)

Question

Which piece of apparatus is used to measure the change in the volume of a liquid most accurately?

▶️ Answer/Explanation

The accuracy of measuring volume depends on the fineness of the scale divisions on the apparatus.
A burette has the finest graduations of the common volume-measuring apparatus, allowing volume changes to be read most precisely.
Beakers and conical flasks only have very approximate volume markings, so they give the least accurate readings.
✅ Answer: (C)

Question

A student breathed gently in and out of the mouthpiece of the apparatus shown.