Three repeated demonstrations with equal samples of a group 1 metal collect hydrogen volumes of 47, 49 and 48 cm³. A separate run collects 31 cm³ after the gas tube becomes loose.
.1
Calculate the mean volume from the three valid repeated demonstrations.
[3 marks]
.2
Explain why the low run cannot show that the metal was less reactive.
[2 marks]
4 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
A student says: "Crude oil is a compound. Fractional distillation breaks its molecules into simpler hydrocarbons. Each fraction contains one pure substance."
Evaluate each part of this explanation.
[4 marks]
4 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
Two laboratory ecosystem models both remove carbon dioxide by photosynthesis. In model A all dead plant material decomposes. In model B some material is buried where decomposition is very slow.
Explain which model better represents long-term carbon removal and why the amount photosynthesised alone is not enough to predict the long-term atmospheric change.
[4 marks]
4 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
A reaction uses the same solution concentration at 20 °C and 35 °C. A student explains the faster reaction at 35 °C by saying particles are larger and the activation energy has decreased.
Evaluate the explanation.
[4 marks]
4 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
A beaker becomes colder when two substances react. A student sketches a reaction profile with products below reactants and no energy barrier.
Explain how the profile should be corrected and what each correction means.
