About Group 2 in A Level Chemistry
Group 2 is one of the 18 main topics in our A Level Chemistry (Cambridge (CAIE) 9701) question bank, and about 6% of its real questions come from it. Tayyari Karo has 41 real questions on this topic from 2021 to 2026, from Paper 1, Paper 2, Paper 4; 30 are multiple choice and marked instantly, and the rest are structured questions with a model answer. By difficulty: 21 medium, 20 hard.
Work through the questions below, then open the explanation for each one. Redo the ones you missed a few days later.
Try 6 real questions
These are real past-paper questions. Think of your answer first, then open the explanation.
May/June 2026 · Paper 1 · Group 2
Which reaction produces the smallest total number of moles of gas? [relative formula mass: CaCO3 100.1; Sr(NO3)2 211.6; BaCO3 197.3]
- 3.60 g magnesium is added to 75.0 cm3 of 3.00 mol dm-3 sulfuric acid
- 16.0 g calcium carbonate is added to 50.0 cm3 of 4.80 mol dm-3 hydrochloric acid
- 10.6 g strontium nitrate is decomposed by heating
- 27.6 g barium carbonate is decomposed by heating
Show answer and explanation
Answer: B. 16.0 g calcium carbonate is added to 50.0 cm3 of 4.80 mol dm-3 hydrochloric acid
A: 0.148 mol H2. B: HCl limiting (0.240 mol) gives 0.120 mol CO2. C: 0.0501 mol Sr(NO3)2 gives 0.125 mol (NO2 + O2). D: 0.140 mol CO2. B is smallest.
October/November 2025 · Paper 1 · Group 2
The trends seen in Group 2 can be used to predict the properties of radium and its compounds. Which statement is correct?
- Radium has the highest second ionisation energy of the elements in Group 2.
- Radium hydroxide is the least soluble of the hydroxides of the elements in Group 2.
- Radium carbonate has the lowest thermal stability of the carbonates of the elements in Group 2.
- Radium reacts faster with water than the other elements in Group 2.
Show answer and explanation
Answer: D. Radium reacts faster with water than the other elements in Group 2.
Reactivity with water increases down Group 2 as ionisation energy decreases, so radium (at the bottom) reacts fastest with water.
October/November 2024 · Paper 1 · Group 2
Compound L decomposes on heating. One of the products is gas M. M reacts with unburned hydrocarbons to form peroxyacetyl nitrate, PAN. What could be the formula of L?
- CaNO3
- Ca(NO3)2
- MgCO3
- Mg(CO3)2
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Answer: B. Ca(NO3)2
PAN is formed from NO2 reacting with hydrocarbons in photochemical smog, so gas M is NO2; thermal decomposition of a Group 2 nitrate, Ca(NO3)2, produces NO2 gas (along with CaO and O2).
October/November 2023 · Paper 1 · Group 2
L and M are both compounds of Group 2 elements. L and M are both soluble in water. When solutions of L and M are mixed, a white precipitate is formed. What could be L and M?
- barium chloride and magnesium sulfate
- barium sulfate and magnesium chloride
- barium nitrate and magnesium chloride
- barium carbonate and magnesium nitrate
Show answer and explanation
Answer: A. barium chloride and magnesium sulfate
Both barium chloride and magnesium sulfate are soluble; mixing them forms insoluble BaSO4 as a white precipitate. (The other options include an already-insoluble Group 2 compound, so they are not both soluble to start with.)
October/November 2022 · Paper 1 · Group 2
The oxides BaO, CaO, MgO and SrO all produce alkaline solutions when added to water. Which oxide produces the saturated solution with the highest pH?
- BaO
- CaO
- MgO
- SrO
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Answer: A. BaO
Solubility (and hence hydroxide concentration/pH) of Group 2 hydroxides increases down the group, so BaO, being lowest in the group among those listed, gives the most alkaline saturated solution.
October/November 2021 · Paper 1 · Group 2
An element, Y, burns in O2 to give a white solid; this dissolves in HCl(aq) to give a solution; adding NaOH(aq) gives a white precipitate; excess NaOH(aq) redissolves it to give a solution. What could element Y be? A Na, B Mg, C Al, D P
- Na
- Mg
- Al
- P
Show answer and explanation
Answer: C. Al
Al2O3/Al(OH)3 is amphoteric, dissolving in excess NaOH(aq) to form [Al(OH)4]−, matching the observations.
