O Levels Chemistry (5070)•5070/12/O/N/18
Explanation
Apparatus for Measuring Mass Increase in Mg-O Reaction
Steps:
- Reaction Mg + ½O₂ → MgO shows mass gain from oxygen absorption.
- Investigation requires weighing magnesium before/after heating to quantify oxygen added.
- Suitable apparatus must allow oxygen entry while containing product to capture full mass change.
- Sets 2 and 3 use lidded crucibles (ajar for gas access) on balance; set 1 lacks containment.
Why C is correct:
- Sets 2 and 3 enable closed-system weighing per conservation of mass, accurately showing oxygen uptake.
Why the others are wrong:
- A includes unsuitable set 1 (open setup loses volatile products).
- B omits sets 2 and 3 needed for controlled mass measurement.
- D excludes set 3, missing a valid lidded option for reaction containment.
Final answer: C
Topic: Experimental design
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