Q. During dehydration what is the substance that is usually lost by the body

Explanation by: Mr. Dubey

During dehydration, the body loses water and essential electrolytes, primarily sodium chloride (NaCl). Sodium plays a crucial role in maintaining fluid balance, nerve function, and muscle contraction.
Sugar → ❌ Not primarily lost during dehydration.
Calcium phosphate → ❌ Important for bones, but not significantly lost in dehydration.
Potassium chloride → ❌ Potassium loss can occur, but sodium chloride is lost in larger amounts.
Thus, Sodium chloride is the correct answer.