Solid calcium oxide was taken in a container and water was added slowly to it.

(i) State two observations made in the experiment.

(ii) Write the balanced chemical equation of this reaction. (2013)

(a) What is meant by balanced chemical equation? Why chemical equations are balanced?

(b) Balance the chemical equation given below:

Al₂O₃ + NaOH → NaAlO₂ + H₂O (2013)

Write balanced chemical equations for the following reactions: (2013)

(a) dilute sulphuric acid reacts with aluminium powder

(b) dilute hydrochloric acid reacts with sodium carbonate

(c) Carbon dioxide is passed through lime water.

Mention the rules for writing a chemical equation illustrating with the help of example. (2013)

Select (i) combination reaction (ii) decomposition reaction and (iii) displacement reaction from the following chemical equations: (2014)

(i) ZnCO₃ (s) → ZnO (s) + CO₂ (g)

(ii) Pb (s) + CuCl₂ (aq) → PbCl₂ (aq) + Cu (s)

(iii) NaBr (aq) + AgNO₃ (aq) → AgBr (s) + NaNO₃ (aq)

(iv) H₂ (g) + Cl₂ (g) → 2 HCl (g)

(v) Fe₂O₃ + 2Al → Al₂O₃ + 2Fe

(vi) 3H₂ (g) + N₂ (g) → 2NH₃ (g)

(vii) CaCO₃ (s) CaO (s) + CO₂ (g)