Classify the following reactions as combination, decomposition, displacement, precipitation and neutralization. Also balance the equations.

(a) CaCO₃ (s) $\xrightarrow{\enspace\Delta\enspace}$ CaO (s) + CO₂ (g)

(b) Zn(s) + H₂SO₄ ⟶ ZnSO₄ (s) + H₂ (g)

(c) AgNO₃ (aq) + NaCl (aq) ⟶ AgCl(s) + NaNO₃

(d) NH₃ (g) + HCl (g) ⟶ NH₄Cl (s)

(e) CuSO₄ (aq) + H₂S (g) ⟶ CuS (s) + H₂SO₄ (l)

(f) Zn (s) + CuSO₄ (aq) ⟶ ZnSO₄ (aq) + Cu(s)

(g) Ca(s) + O₂ (g) ⟶ CaO(s)

(h) NaOH + HCl ⟶ NaCl + H₂O

(i) KOH + H₂SO₄ ⟶ K₂SO₄ + H₂O

Write the missing reactants and products and balance the equations:

(a) NaOH + …………… ⟶ NaCl + …………….

(b) KClO₃ $\xrightarrow{\text{heat}}$ …………….. + ……………….

(c) …………. + HCl ⟶ NaCl + H₂O + ……………..

What do you observe (on the basis of energy)when:

(a) an acid is added to a basic solution?

(b) ammonium chloride is dissolved in water?

Define:

(a) Precipitation

(b) Neutralization

(c) Catalyst

(d) Alkali