The three products are:
Sodium hydroxide (NaOH), Chlorine (CI₂) and Hydrogen (H₂).
NaOH - for soaps and detergents and paper making or artificial fibers.
Cl₂- PVC, pesticides, CFCs.
H₂- fuels, margarine, NH3 for fertilizers.

(i) Mg + 2HCl\(\rightarrow\)MgCl₂+H₂
Hydrogen gas is produced
(ii) HCl + NaOH\(\rightarrow\) NaCl+H₂O
Neutralisation reaction
(iii) 2HCI(aq)+ CaCO₃(aq)\(\rightarrow\)CaCl₂(aq)+H₂O+CO₂
Calcium chloride is formed.

It is a salt produced by the neutralization reaction between a strong base (NaOH) and a weak acid (H₂CO₃), hence it is a basic salt.
It is heated strongly to produce sodium carbonate
\(2NaCO_3 \xrightarrow{Delta} Na_2CO_3 + H_2O + CO_2\)
Sodium carbonate is recrystallized to produce washing soda
\(Na_2CO_3 + 10H_2O \longrightarrow Na_2CO_3.10H_2O\)

(i) Salt that contains water of crystallisation.
(ii)Washing soda - Na₂CO₃.10H₂O
Gypsum - CaSO₄.2H₂O
Plaster of pans - CaSO₄.\(1\over 2\)H₂O

Water of crystallisation is a fixed number of water molecules present in one formula unit of a salt. One formula unit of copper sulphate contains five water molecules (SH₂O). The water molecules which form
part of the structure of a crystal are called water of crystallisation.
\(\underset{(Hydrated\ copper\ sulphate)\\(Blue)}{CuSO_4.5H_2O}\xrightarrow{Heat}\underset{(Anhydrous\ copper\ sulphate)\\(White)}{CuSO_4}+\underset{Water\\(Goes\ away)}{5H_2O}\)
Due to loss of water of crystallisation.
\(\underset{Anhydrous\ copper\ sulphate\\(White)}{CUSO_4}+\underset{Water}{5H_2O}\longrightarrow\underset{Hydrated\ sulphate\\(blue)}{CUSO_4.5H_2O}\)
By adding water

They react with metals to give out hydrogen gas.
e.g.,
Zn + 2HCI\(\rightarrow\)ZnCl₂+H₂
(ii) They react with bases to form salt and water. e.g.,
2NaOH +H₂SO₄\(\rightarrow\)Na₂SO₄+2H₂O
(iii) They react with metal carbonates to liberate CO₂ gas
Na₂CO₃+2HCl\(\rightarrow\)2NaCl+H₂O+CO₂

(i) The acid is to be added slowly in water to prevent the mixture to be splashed. The reaction is highly exothermic, therefore, constant cooling should be done.
(ii) The process is called dilution.

(i) Tomato - Malic acid and citric acid
(ii) Vinegar - Acetic acid
(iii) Tamarind - Tartaric acid and citric acid.

Acids which ionize completely in aqueous solution-strong acids.
Acids which ionize partially in aqueous solution-weak acids.
Hydrochloric acid, nitric acid-strong acid.
Acetic acid, formic acid-weak acid.

(i) Sodium carbonate (washing soda) is used in glass, soap and paper industries.

(ii) It is used in the manufacture of sodium compounds such as borax.

(iii) Sodium carbonate can be used as a cleaning agent for domestic purposes.

(iv) It is used for removing permanent hardness of water.

(i) The raw materials used in the manufacture of sodium carbonate by Solvay process are calcium carbonate \((CaCO_3)\),  ammonia gas \((NH_3)\), and sodium chloride solution \((NaCl)\).

(ii) Sodium hydrogen carbonate formed during Solvay process is separated from a mixture of \(NH_4Cl\) and \(NaHCO_3\) by the method of filtration.

(iii) Sodium carbonate is obtained from sodium hydrogen carbonate by heating it and then adding calculated amount of water into its.

Plaster of Paris is calcium sulphate hemihydrate \((CaSO_4.{1\over2}H_2O).\)

Gypsum, when heated at a temperature of about 380 K in a kiln. loses its three-fourth water of crystallisation and changes to plaster of Paris.

Following is the reaction involved:

\(\underset{Gypsum}{CaSO_4.2H_2O}\xrightarrow {Heat} \underset{Plaster\ of\ Paris}{CaSO_4.{1\over2}H_2O}+\underset{Water}{1{1\over2}H_2O}\)