question_answer

Value    of   \[x\]    in   potash    alum, \[{{K}_{2}}S{{O}_{4}}.A{{l}_{x}}{{(S{{O}_{4}})}_{3}}.24{{H}_{2}}O\]

A) 4                             

B)        1                             

C) 2                             

D)        None of these

Correct Answer: C

Solution :

Key Idea Potash alum is a double salt. Potash   alum,\[{{K}_{2}}S{{O}_{4}}.A{{l}_{x}}{{(S{{O}_{4}})}_{3}}.24{{H}_{2}}O\](given) Therefore,\[A{{l}_{2}}{{(S{{O}_{4}})}_{3}}\] is compound of \[A{{l}^{3+}}\]and\[SO_{4}^{2-}.\] On comparing, \[x=2\] Hence, formula of potash alum is = \[{{K}_{2}}S{{O}_{4}}.A{{l}_{2}}{{(S{{O}_{4}})}_{3}}.24{{H}_{2}}O\]