Compound A reacts with NH _ 4 Cl and forms a compound B. Compound B...

When calcium hydroxide is reacted with crystals of ammonium chloride, the products formed as calcium chloride, ammonia and water.

$Ca ( OH{)}_{2} + {NH}_{4}Cl \to {CaCl}_{2} + 2{NH}_{3} + 2{H}_{2}O$

When ammonia is reacted with water and excess carbon dioxide, it forms ammonium hydrogen carbonate which on passing through with saturated NaCl solution forms hydrogen carbonate.

${NH}_{3} + {H}_{2}O + {CO}_{2} \to {NH}_{4}{HCO}_{3}$

${NH}_{4}{HCO}_{3} + NaCl \to {NaHCO}_{3} ↓ + {NH}_{4}Cl$

So, the compound A, B, and C are $Ca ( OH{)}_{2}, N{H}_{3}, N{H}_{4}HC{O}_{3}$ respectively.