What is the correct formula for "Mohr's salt"?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → \(FeSO_4.(NH_4)_2SO_4.6H_2O\)
Mohr’s salt is the double salt ferrous ammonium sulphate hexahydrate: iron is in the +2 state (ferrous sulphate, \( \ce{FeSO4} \)) and there are six molecules of water of crystallisation. In water it gives its simple ions:
\( \displaystyle \ce{FeSO4.(NH4)2SO4.6H2O -> Fe^2+ + 2NH4+ + 2SO4^2- + 6H2O} \)
NCERT (2026-27 edition):
Difference between a Double Salt and a Complex
