The newest 20 of 25 written questions. Open one to see it on the real paper.
The word equation for the reaction between calcium and oxygen is shown. calcium + oxygen — calcium oxide 5.0g of calcium reacts completely with 2.0g of oxygen. Calculate the mass of oxygen that reacts completely with 40.0g of calcium. mass of oxygen = . -g
See it on the paper →Nitrogen is used in the manufacture of fertilisers. A bag of fertiliser contains 7.36 kg of ammonium nitrate, NH,NOs. Calculate the number of moles of ammonium nitrate in the bag of fertiliser. [M,: NH,NO3, 80] moles ammonium nitrate
See it on the paper →Determine the relative molecular mass, M r , of ethane, C 2 H 6 . [A r : C, 12; H, 1] relative molecular mass, M r =
See it on the paper →Determine the relative molecular mass, M r , of ethane, C 2 H 6 . [A r : C, 12; H, 1] relative molecular mass, M r =
See it on the paper →Calcium carbonate (limestone) is added to the blast furnace to remove impurities from the hematite. The calcium carbonate thermally decomposes to make calcium oxide and carbon dioxide. CaO + CO 2 CaCO 3 Calculate the mass of calcium carbonate needed to make 7 tonnes of calcium oxide. [A r : C, 12; Ca, 40; O, 16] mass o...
See it on the paper →Carbon is used to extract an element, X, from its oxide. The equation for the reaction is shown. XO 2 + C X + CO 2 The sum of the relative formula masses of the reactants (XO 2 + C) is 163. [A r : C, 12; O, 16] relative atomic mass of X = Calculate the relative atomic mass of X.
See it on the paper →The equation for the reaction is shown. 2Al + Fe 2 O 3 2Fe + Al 2 O 3 A mixture contains 162 g of aluminium and 800 g of iron oxide. Show that aluminium is the limiting reactant. [A r : Al, 27; Fe, 56; O, 16] (c) Iron is extracted from iron oxide by reacting the iron oxide with aluminium. aluminium is the limiting reac...
See it on the paper →Calculate the percentage of carbon in the alloy. percentage = %
See it on the paper →The mass of the spanner is 80 g. Calculate the mass of chromium contained in the spanner. mass of chromium = g
See it on the paper →Calculate the maximum mass of sulfur trioxide that is made from 1.6 kg of sulfur dioxide. [A r : O, 16; S, 32] mass of sulfur trioxide = kg
See it on the paper →A sample of brass has a mass of 250 g. The sample of brass has the composition shown in Table 11.1. Table 11.1 metal % composition lead 2 copper 65 zinc 33 Calculate the mass of zinc contained in the sample of brass. mass of zinc = g
See it on the paper →Iron is extracted from hematite in a blast furnace. One stage of this process involves the reaction of iron oxide, Fe 2 O 3 , with carbon monoxide. Fe 2 O 3 + 3CO 2Fe + 3CO 2 Calculate the mass of iron made when 400 kg of iron oxide reacts with excess carbon monoxide. [A r : Fe, 56; O, 16] mass of iron = kg
See it on the paper →Calculate the percentage of magnesium contained in the alloy. percentage of magnesium = %
See it on the paper →Calculate the mass of aluminium contained in 20 kg of the alloy. mass of aluminium = kg
See it on the paper →Duralumin is an alloy of aluminium. Table 2.1 shows the percentage composition of duralumin. Table 2.1 metal percentage by mass in the alloy / % aluminium 95 copper 4 magnesium 1 Calculate the mass of aluminium in 20 kg of duralumin. mass of aluminium = kg
See it on the paper →A student makes another fertiliser called potassium sulfate, K 2 SO 4 . The reactants are potassium hydroxide, KOH, and sulfuric acid, H 2 SO 4 . 2KOH + H 2 SO 4 K 2 SO 4 + 2H 2 O Calculate the maximum mass of potassium sulfate made from 28 g of potassium hydroxide. Show your working. [A r : H, 1; K, 39; O, 16; S, 32]...
See it on the paper →Aluminium reacts with oxygen to make aluminium oxide, Al 2 O 3 . 4Al + 3O 2 2Al 2 O 3 Calculate the maximum mass of aluminium oxide that can be made from 1.35 g of aluminium. Show your working. mass of aluminium oxide = g
See it on the paper →Calculate the mass of magnesium in 2000 kg of this alloy. mass = kg
See it on the paper →Calculate the maximum mass of magnesium chloride that can be made from 0.48 g of magnesium. Show your working. [A r : Cl , 35.5; Mg, 24] mass = g
See it on the paper →Calculate the mass of magnesium in 500 kg of the alloy. kg
See it on the paper →Comprehensive responses • Some candidates were able to calculate the correct number of moles, using the correct formula and showing their working. Limited responses • Some candidates did not convert kg to g giving a value of 0.092. • Some candidates multiplied the mass by the relative formula mass instead of dividing.
— Examiner report, February/March 2026, 0654/42 Q5(c) (Cambridge)
The correct Mr for CaCO3 was frequently seen. Not all candidates realised that the Mr for CaO also needed to be calculated and used to obtain the final answer. Commonly seen incorrect answers were 7 and 700.
— Examiner report, May/June 2025, 0654/41 Q7(d) (Cambridge)
Some candidates correctly determined the mass as 83 g or 82.5 g.
— Examiner report, February/March 2024, 0654/32 Q11(b)(ii) (Cambridge)
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