Which of the following formula correctly represents the double salt "Carnallite"?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → \(KCl.MgCl_2.6H_2O\)
A double salt is formed when two simple salts crystallise together in a fixed ratio. Unlike a complex, it dissociates completely into simple ions in water. Carnallite is the double salt of potassium chloride and magnesium chloride with six molecules of water, \( \ce{KCl.MgCl2.6H2O} \):
\( \displaystyle \ce{KCl.MgCl2.6H2O(s) -> K+(aq) + Mg^2+(aq) + 3Cl^-(aq) + 6H2O} \)
NCERT (2026-27 edition):
Difference between a Double Salt and a Complex
