Students compare two catalysts for the decomposition of hydrogen peroxide. Each trial lasts 60 s; the same solution volume and concentration are available.
Plan an investigation to compare the rates fairly and assess whether a catalyst is used up.
[6 marks]
4 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
A polymer model contains 150 chains. Each chain contains 400 repeat units.
.1
Calculate the total number of repeat units represented.
[2 marks]
.2
Explain why this model represents a polymer rather than a giant covalent lattice.
[2 marks]
4 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
A solid expected to melt sharply at 156 °C instead melts over 148-153 °C. Its chromatogram shows one visible spot in one solvent.
Evaluate the claim that the single spot proves the solid is pure.
[4 marks]
4 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
A faulty heater produces carbon monoxide. The gas cannot be reliably detected by sight or smell. A student suggests using visible soot as the only warning of danger.
Evaluate this suggestion and explain the health risk of carbon monoxide.
[4 marks]
4 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
A town collects 12 tonnes of glass. Sorting removes 8% as contamination. All remaining glass can replace virgin glass material in this simplified model.
.1
Calculate the mass available to replace virgin material.
[2 marks]
.2
Explain why reducing packaging use can give benefits beyond recycling the same mass.
