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 model of early Earth’s atmosphere is based on gases from present-day volcanoes and comparisons with other rocky planets. There are no direct samples of the complete atmosphere from four billion years ago.
Evaluate the strength and limitations of this evidence.
[4 marks]
5 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
Chlorine atoms have electron arrangement 2,8,7. Iodine atoms have more occupied electron shells but also seven outer electrons.
.1
Explain why chlorine is more reactive than iodine.
[3 marks]
.2
Compare this trend with the reactivity trend down group 1.
[2 marks]
4 marksHigher
Spec and skills
Original practice question
Answer and supported method checks
A refinery has 60 tonnes of a long-chain fraction but buyers want only 20 tonnes. Catalytic cracking converts 75% of the 40-tonne surplus into shorter fuel molecules; the rest becomes other useful products.
.1
Calculate the mass of shorter fuel molecules obtained from the surplus.
[2 marks]
.2
Explain why cracking is useful and state one chemical test that distinguishes an alkene product from an alkane.
[2 marks]
4 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
Three noble gases have boiling points: helium −269 °C, neon −246 °C and argon −186 °C.
.1
Calculate the rise in boiling point from helium to argon.
[2 marks]
.2
Describe the trend and predict whether krypton, below argon, boils above or below −186 °C.
