Which among the following are present in higher amount in hard water?

Correct option is A

✅ (a) Calcium and Magnesium: • Hardness of water is primarily caused by dissolved calcium (Ca²⁺) and magnesium (Mg²⁺) salts. • These ions originate from limestone, gypsum, and dolomite rocks. • They form insoluble salts with soap, reducing its cleaning power.
❌ (b) Calcium and Potassium: • Potassium is not typically responsible for water hardness.
❌ (c) Potassium and Magnesium: • Potassium does not contribute significantly to hardness.
❌ (d) Sodium and Calcium: • Sodium increases water salinity, not hardness.