AS Level Chemistry chapter 10: Group 2 MCQs with answers
By Team Megalecture · Updated 4 Nov 2026
22 exam-style questions on Group 2, each with the answer and a short explanation. Ten of them are below to try. The chapter test draws ten fresh questions each time and is marked the moment you finish, with your score by topic.
Similarities and trends in the properties of the Group 2 metals, magnesium to barium22 questions · notes and questions
Ten Group 2 questions with answers
Try each one, then open the answer. These ten stay the same; the test draws new ones every time.
1. Which equation shows the thermal decomposition of calcium nitrate?
A
Ca(NO3)2 → Ca(NO2)2 + O2
B
2Ca(NO3)2 → 2CaO + 4NO + 3O2
C
Ca(NO3)2 → CaO + 2NO2 + O2
D
2Ca(NO3)2 → 2CaO + 4NO2 + O2
Show answer
Answer: D. Group 2 nitrates decompose to the oxide, brown nitrogen dioxide and oxygen. O atoms: 12 on the left and 2 + 8 + 2 = 12 on the right. Ca(NO3)2 → CaO + 2NO2 + O2 has 7 O on the right, and forming a nitrite is not Group 2 behaviour.
2. Which list gives the Group 2 nitrates in order of increasing temperature needed for thermal decomposition?
A
Ba(NO3)2, Sr(NO3)2, Ca(NO3)2, Mg(NO3)2
B
Ca(NO3)2, Mg(NO3)2, Sr(NO3)2, Ba(NO3)2
C
Mg(NO3)2, Ba(NO3)2, Ca(NO3)2, Sr(NO3)2
D
Mg(NO3)2, Ca(NO3)2, Sr(NO3)2, Ba(NO3)2
Show answer
Answer: D. Thermal stability increases down the group: the larger cations polarise the nitrate ion less, so more heat is needed. Magnesium nitrate decomposes most easily and barium nitrate least easily.
3. Which property decreases from magnesium to barium?
A
atomic radius
B
thermal stability of the carbonate
C
first ionisation energy
D
solubility of the hydroxide
Show answer
Answer: C. Down Group 2 the outer electron is further from the nucleus and more shielded, so first ionisation energy decreases. Atomic radius, carbonate stability and hydroxide solubility all increase down the group.
4. Barium reacts steadily with dilute hydrochloric acid, but its reaction with dilute sulfuric acid soon stops. Why?
A
an insoluble layer of barium sulfate forms on the metal and prevents further reaction
B
barium is not reactive enough to release hydrogen from sulfuric acid
C
sulfuric acid is a weaker acid than hydrochloric acid
D
barium hydroxide precipitates and neutralises the acid
Show answer
Answer: A. BaSO4 is insoluble, so as it forms it coats the barium and stops the acid reaching the metal. BaCl2 is soluble, so the reaction with HCl continues.
5. Saturated aqueous solutions of Mg(OH)2, Ca(OH)2 and Ba(OH)2 are prepared at 25 °C. Which list gives them in order of increasing pH?
A
Ba(OH)2, Ca(OH)2, Mg(OH)2
B
Ca(OH)2, Mg(OH)2, Ba(OH)2
C
Mg(OH)2, Ba(OH)2, Ca(OH)2
D
Mg(OH)2, Ca(OH)2, Ba(OH)2
Show answer
Answer: D. Hydroxide solubility increases down Group 2, so a saturated solution of Ba(OH)2 contains the most OH− ions and has the highest pH. Mg(OH)2 is only sparingly soluble, giving the lowest pH.
6. Why does the reactivity of the Group 2 metals with water increase from magnesium to barium?
A
The metallic bonding gets stronger down the group.
B
The hydroxides formed get less soluble down the group.
C
The nuclear charge increases, so the outer electrons are attracted more strongly.
D
The outer electrons are further from the nucleus and more shielded, so they are lost more easily.
Show answer
Answer: D. The metals react by losing two electrons. Down the group the sum of the first two ionisation energies falls because the outer electrons are further away and more shielded, outweighing the larger nuclear charge.
7. Barium carbonate must be heated to a much higher temperature than magnesium carbonate before it decomposes. Why?
A
Ba2+ is larger, with a lower charge density, so it polarises (distorts) the carbonate ion less
B
the Ba–O bond is stronger than the Mg–O bond
C
barium is a more reactive metal
D
BaCO3 has a higher molar mass
Show answer
Answer: A. A small, highly charged cation such as Mg2+ pulls electron density away from the carbonate ion, weakening its C–O bonds so it breaks up to CO2 at a lower temperature. Thermal stability therefore increases down the group.
8. Which gases are produced when magnesium nitrate is heated strongly?
A
NO2 and O2
B
NO and O2
C
N2 and O2
D
N2O only
Show answer
Answer: A. Group 2 nitrates decompose to the metal oxide, nitrogen dioxide and oxygen: 2Mg(NO3)2 → 2MgO + 4NO2 + O2. The brown fumes seen are NO2.
9. Separate samples of four barium compounds are added to dilute hydrochloric acid. Which one fizzes?
A
BaO
B
Ba(OH)2
C
BaSO4
D
BaCO3
Show answer
Answer: D. BaCO3 + 2HCl → BaCl2 + H2O + CO2; the carbon dioxide causes the fizzing. The oxide and hydroxide are neutralised without any gas, and BaSO4 does not react.
10. 2.10 g of magnesium carbonate reacts with excess dilute sulfuric acid. What volume of carbon dioxide is produced at room conditions?
A
0.299 dm3
B
0.598 dm3
C
1.20 dm3
D
2.10 dm3
Show answer
Answer: B. MgCO3 + H2SO4 → MgSO4 + H2O + CO2. Mr(MgCO3) = 84.3, so n = 0.0249 mol and V = 0.0249 × 24.0 = 0.598 dm3. MgSO4 is soluble, so the reaction goes to completion.
22, each with the answer and a short explanation, across 1 topics: Similarities and trends in the properties of the Group 2 metals, magnesium to barium. Every chapter test draws ten of them, so you can take it many times.
Is the AS Level Chemistry chapter 10 test free?
Yes. The test, the answers and the explanations are free and need no sign-up. Sign in only if you want your scores kept across devices.
How is the chapter test marked?
The moment you press Finish: your score, the right answer and an explanation for every question, and the ones you got wrong saved in My mistakes to retry.
