Consider the following statements: 1. The temporary hardness in water is due to the presence of bicarbonates of calcium. 2. The permanent hardness in water is due to the presence of soluble chlorides and sulphates of calcium and magnesium. 3. The permanent hardness in water is removed by adding Na2CO3 to water. Which of the statements given above are correct?

All three statements are scientifically accurate regarding the chemistry of water hardness:

• Statement 1: Temporary hardness is caused by the presence of dissolved bicarbonates of calcium and magnesium. It is termed 'temporary' because it can be removed simply by boiling, which precipitates the salts as insoluble carbonates.
• Statement 2: Permanent hardness is due to the soluble chlorides and sulphates of calcium and magnesium. These salts remain in solution even after boiling, requiring chemical methods for removal.
• Statement 3: Permanent hardness can be removed by treating water with washing soda (Sodium Carbonate, Na2CO3). The sodium carbonate reacts with the soluble calcium and magnesium chlorides/sulphates to form insoluble carbonates (like CaCO3), which precipitate out and can be filtered, thereby softening the water.