What is the correct sequence of the following salts in ascending order according to their presence in the sea water?

Select the answer using the code given below:

(a) 3, 1, 2

(b) 1, 3, 2

(c) 1, 2, 3

(d) 2, 1, 3

Answer: (a) 3, 1, 2

Explanation:

● Magnesium Chloride (MgCl₂) is formed from Magnesium (Mg²⁺) and Chloride (Cl⁻), which are highly abundant in seawater. Hence, it has the highest concentration among the given salts.

● Calcium Sulphate (CaSO₄) is formed from Calcium (Ca²⁺) and Sulphate (SO₄²⁻). Sulphate is abundant, but Calcium is less so, giving it an intermediate concentration.

● Calcium Carbonate (CaCO₃) is formed from Calcium (Ca²⁺) and Carbonate ions. Both are present in relatively lower concentrations, and CaCO₃ has low solubility, causing precipitation and reducing its dissolved presence in seawater.

● Therefore, in ascending order of typical presence in seawater, the sequence is:
Calcium Carbonate < Calcium Sulphate < Magnesium Chloride

The major dissolved ions in seawater, in order of decreasing concentration, are:

1. Chloride (Cl⁻)
2. Sodium (Na⁺)
3. Sulfate (SO₄²⁻)
4. Magnesium (Mg²⁺)
5. Calcium (Ca²⁺)
6. Potassium (K⁺)
7. Bicarbonate (HCO₃⁻)
8. Bromide (Br⁻)
9. Borate (B(OH)₄⁻)
10. Strontium (Sr²⁺)

Answer: (a) 3, 1, 2