Question

Mohr’s salt is a:
(a)- Normal salt
(b)- Acid salt
(c)- Basic salt
(d)- Double salt

Answer 1

There are two forms of Mohr's salt, i.e., hydrated whose formula is $Fe(S{{O}_{4}}){{(N{{H}_{4}})}_{2}}(S{{O}_{4}}).6{{H}_{2}}O$ and anhydrous form whose formula is $Fe(S{{O}_{4}}){{(N{{H}_{4}})}_{2}}(S{{O}_{4}})$. Normal salts are those in which all the hydrogen atoms are replaced with metal ions, acidic salts are those which form acidic solution, basic salts are those which form basic solution, and double salt is the salts in which there are either two types of cations or two types of anions.

Complete answer:
Salt is a compound in which there are two types of substances present, i.e., cations which are the positive part, and anions which are the negative part.
Normal salts are those in which all the hydrogen atoms are replaced with metal ions.
Acidic salts are those which form an acidic solution when it is dissolved in water.
Basic salts are those which form a basic solution when dissolved in water.
Double salts are the salts in which there are either two types of cations or two anions.
The given compound is Mohr’s salt, which is also known as Ammonium iron (II) sulfate or Ferrous ammonium sulfate. There are two forms of Mohr’s salt, i.e., hydrated whose formula is $Fe(S{{O}_{4}}){{(N{{H}_{4}})}_{2}}(S{{O}_{4}}).6{{H}_{2}}O$ and anhydrous form whose formula is $Fe(S{{O}_{4}}){{(N{{H}_{4}})}_{2}}(S{{O}_{4}})$.
So, in this there are two type of cations and one anion, i.e., $F{{e}^{2+}}$, $NH_{4}^{+}$, and $SO_{4}^{2-}$. Therefore, there are two types of cations, it is double salt.

Hence, the correct answer is an option (d)- Double salt.

Note:
The molecular mass of hydrated Mohr’s salt is 392.13 g /mol and the molecular mass of anhydrous Mohr’s salt is 284.05 g /mol. Mohr’s salt is a solid whose color is blue-green.