Both sodium and potassium are present in equal abundance in the earth's crust, but sodium is about 30 times as abundent as potassium in oceans. Give reasons.

Explanation

As compared to sodium, potassium is larger in size. Therefore, potassium salt with larger anions are less soluble and thus retained behind, while more soluble sodium salts are carried to the sea. Also potassium is strongly bound with complex silicates and aluminosilicates in the soil and are thus retalined. Potassium ion are preferentially absorbed by plants wheres sodium ions proceed to the sea.