Group 2 STPM

The carbonate of a Group 2 element (beryllium to barium) in the Periodic Table, MCO₃, decomposes on heating. Which of the following explains why the thermal stability of MCO₃ increases down Group 2? [2005, Q25]

• The radius of M²⁺ ion increases

• The lattice energy of MCO₃ decreases

• The charge density of M²⁺ ion decreases

• The distance between M²⁺ and CO₃^2- ions increases.

Strontium is an element in Group 2 of the Periodic Table which is situated between calcium and barium. Which statement is true?

• The strontium ion has a higher charge density than the calcium ion

• Strontium sulphate is less soluble in water than calcium sulphate.

• Strontium carbonate is more difficult to decompose than barium carbonate when heated

• Strontium nitrate is more difficult to decompose than barium nitrate when heated

When aqueous solutions of barium nitrate and sodium sulphate are mixed, a white precipitate of barium sulphate is formed. Which statement explains why barium sulphate is precipitated from the reaction mixture? [2013 U2, Q10]

• Its ions are large

• It is an ionic compound with covalent character

• Its enthalpy of hydration is lower than its lattice energy

• It has a high solubility product

Which element has a value of electronegativity closer to aluminium? [2013 U2, Q11]

• Beryllium

• Magnesium

• Strontium

• Barium

Which reaction shows the strong heating of magnesium nitrate?

• Mg(NO₃)₂ --> Mg(NO₂)₂ + O₂

• Mg(NO₃)₂ -->MgO₂ + 2NO₂

• Mg(NO₃)₂ --> MgO + N₂O + 2O₂

• 2Mg(NO₃)₂ --> 2MgO + 4NO₂ + O₂

Magnesium is a Group 2 element. When magnesium carbonate is heated, magnesium oxide is formed and carbon dioxide is liberated.

MgCO₃ --> MgO + CO₂

Which of the following is true when going down the group?

• Lattice energy of carbonates decreases

  Lattice energy of oxides decreases

  Thermal stabilities of oxide decreases

• Lattice energy of carbonates decreases

  Lattice energy of oxides decreases

  Thermal stabilities of oxide increases

• Lattice energy of carbonates increases

  Lattice energy of oxides increases

  Thermal stabilities of oxide decreases

• Lattice energy of carbonates decreases

  Lattice energy of oxides increases

  Thermal stabilities of oxide decreases

A solution of aluminium nitrate will turn blue litmus paper to red because

• the Al³⁺ ion is hydrolysed

• the Al³⁺ ion has a high charge

• all aluminium compounds are acidic

• aluminium nitrate is an ionic compound

Beryllium is a Group 2 element. Which of the following is the anomalous properties of beryllium?

• Beryllium oxide is amphoteric

• Beryllium chloride does not dissolve in water

• Beryllium forms a covalent compound with fluorine

• Beryllium oxide can form dimer.

The solubilities of the sulphates of Group 2 metals decrease down the group because

• the cation size increases from Mg²⁺ to Ba²⁺

• the hydration energy of the cations becomes less exothermic from Mg²⁺ to Ba²⁺

• the sulphates ion very much smaller than these cations.

The carbonates, nitrates and hydroxides of Group 2 elements decompose to their respective oxides when heated. Hence, it can be concluded that

• all compounds of Group 2 elements are unstable to heat

• Group 2 elements are strong reducing agents

• the oxide is energetically more stable than the carbonates, nitrates and hydroxides

• the metallic properties of the elements increases down the Group