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 farm reduces methane emissions from manure handling from 15 tonnes CO2-equivalent to 9 tonnes per year. New equipment adds 2 tonnes CO2-equivalent per year from energy use. All other emissions are unchanged.
.1
Calculate the net annual reduction in the farm’s footprint.
[2 marks]
.2
Explain why methane and carbon dioxide emissions both matter, and suggest one implementation barrier.
[2 marks]
5 marksHigher
Spec and skills
Original practice question
Answer and supported method checks
A bottle contains carbon dioxide molecules. A sample of magnesium chloride contains Mg2+ and Cl− ions.
.1
Compare how bonds form in the two substances.
[3 marks]
.2
Explain why one magnesium atom needs two chlorine atoms to form the compound.
[2 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]
6 marksHigher
Spec and skills
Original practice question
Answer and supported method checks
Copper oxide is reduced by hydrogen: CuO+H2→Cu+H2O. A process must produce 12.8 g copper. Ar: Cu = 64, O = 16, H = 1.
.1
Calculate the minimum mass of copper oxide needed if conversion is complete.
[4 marks]
.2
Calculate the mass of hydrogen that reacts with this copper oxide.
