"Name the products formed in each case when:

a. Hydrochloric acid reacts with caustic soda

b. Granulated zinc reacts with caustic soda

c. Carbon dioxide is passed into the lime water."

(a) When HCl (an acid) reacts with caustic soda (NaOH – a base), form salt, i.e., sodium chloride (NaCl). The reaction is given as:

NaOH + HCl → NaCl + H₂O

(b) When zinc granules are heated with caustic soda (sodium hydroxide), produce sodium zincate (Na₂ZnO₂) and hydrogen gas. The reaction is:

Zn + 2NaOH → Na₂ZnO₂ + H₂

Note: When a metal and a base react with each other, they form a metal salt and hydrogen gas.

In the above reaction, zinc is a metal and sodium hydroxide is a base. When they combine, give a metal salt, i.e., sodium zincate and hydrogen gas are formed.

(c) Reaction of lime water (calcium hydroxide) with CO₂ which turns lime water milky:

Ca(OH)₂ + CO₂→ CaCO₃ + H₂O