(a) State the chemical property in each case on which the following uses of baking soda are based upon: (i) as an anti-acids (ii) as a constituent in making baking powder (iii) in soda-acid fire-extinguishers OR (b) Write chemical equations to show what happens when an acid reacts with a (i) metal (ii) base and (iii) carbonate. Write the name of the main product formed in each case.

(a) (i) Baking soda is used as an antacid because it is a base and can neutralize excess acid in the stomach. The chemical reaction is: NaHCO3 + HCl $\rightarrow$ NaCl + H2O + CO2 (ii) Baking soda is used as a constituent in making baking powder because it releases carbon dioxide gas when it comes into contact with an acid and heat. The chemical reaction is: NaHCO3 + H+ $\rightarrow$ Na+ + H2O + CO2 (iii) Baking soda is used in soda-acid fire-extinguishers because it releases carbon dioxide gas when it comes into contact with an acid. The chemical reaction is: NaHCO3 + H+ $\rightarrow$ Na+ + H2O + CO2 OR (b) (i) When an acid reacts with a metal, it produces a salt and hydrogen gas. The chemical reaction is: 2HCl + Zn $\rightarrow$ ZnCl2 + H2 (ii) When an acid reacts with a base, it produces a salt and water. The chemical reaction is: HCl + NaOH $\rightarrow$ NaCl + H2O (iii) When an acid reacts with a carbonate, it produces a salt, water, and carbon dioxide gas. The chemical reaction is: 2HCl + Na2CO3 $\rightarrow$ 2NaCl + H2O + CO2