UPSC CDS Science Chemistry Questions Part 1

Among the given items, first and second substance causes temporary hardness in water.
There are two types of water hardness: temporary and permanent hardness.
Temporary hardness: due to the presence of calcium hydrogen carbonate Ca(HCO3)2(aq) and magnesium hydrogen carbonate Mg(HCO3)2(aq)
Permanent hardness: due to thepresence of the chlorides, nitrates and sulphates of calcium and magnesium.
Temporary hardness can be removed by boiling the water but permanent hardness cannot be removed by boiling.