Beryllium is a Group 2 element. Using dot-and-cross diagrams, and showing the outer electrons only, draw the electronic configurations of beryllium and oxygen before and after bonding.

Limewater is a solution of calcium hydroxide. Explain why calcium hydroxide is used in agriculture.

Exactly $0.1 \mathrm{moles}$ each of calcium hydroxide and barium hydroxide are added to separate beakers containing $100 {\mathrm{cm}}^3$ of water and stirred to form saturated solutions. Explain which solution has the higher pH value.

For the following reaction, state which element is oxidised and which is reduced, and give the changes in oxidation number.

$\mathrm{Sr} + {\mathrm{Cl}}_2 \to {\mathrm{SrCl}}_2$

For the following reaction, state which element is oxidised and which is reduced, and give the changes in oxidation number.

$\mathrm{Sr}+ 2{\mathrm{H}}_2\mathrm{O} \to \mathrm{Sr}{\left(\mathrm{OH}\right)}_2 + {\mathrm{H}}_2$

For the following reaction, state which element is oxidised and which is reduced, and give the changes in oxidation number.

$2\mathrm{Mg} + {\mathrm{CO}}_2 \to 2\mathrm{MgO} + \mathrm{C}$