Question:

The temporary hardness of a water sample is due to compound X. Boiling this sample converts X to compound Y. X and Y, respectively, are:

Ca(HCO3)2andCaO

Mg(HCO3)2andMg(OH)2

Ca(HCO3)2andCa(OH)2

Mg(HCO3)2andMgCO3

Correct option is C. Mg(HCO3)2 and Ca(HCO3)2
Temporary hardness is due to soluble Mg(HCO3)2 and Ca(HCO3)2
Mg(HCO3)2 →Boil→ Mg(OH)2↓ + 2CO2↑