Question

Assertion: \[{{K}_{2}}S{{O}_{4}}.A{{l}_{2}}{{(S{{O}_{4}})}_{3}}.24{{H}_{2}}O\] is a double salt compound.
Reason: It ionises to give a complex ion.
(A) Both Assertion and Reason are correct and the Reason is the correct explanation for Assertion.
(B) Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.

Answer 1

Hint: Alum is a colourless, hydrated, double sulphate of potassium and aluminium. \[{{K}_{2}}S{{O}_{4}}.A{{l}_{2}}{{(S{{O}_{4}})}_{3}}.24{{H}_{2}}O\] is a double salt, known as Potash Alum. It dissociates into Potassium ions, Aluminium ions, and two Sulphate ions.

Complete step by step answer:
- A double salt is a compound which essentially contains an anion and cation in the combination of two different salts with different crystal structures.
- Alum is a group of hydrated double salts. One such example of this is Potash alum.
- Potash alum is an example of double salt. It is commonly found in nature as dodecahydrate.
- Dodecahydrate is a solid molecule containing twelve molecules of water of crystallization.

Therefore, option (B) is the correct answer. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.

Additional information: Alum is commonly used in the form of face cream and gel. It shows properties that are good for skin tightening. Because of the astringent property of alum, it is also used as an antiseptic ointment for blood wounds.

Note: Potash alum is widely used in the medicine industry and water purification methods. This compound is not a complex salt. Being a double salt, it dissociates further to give different ions.