question_answer

Hydrogen ion concentration in mol/L in a solution of\[pH=5.4\]will be     AIEEE  Solved  Paper-2005

A) \[3.98\times {{10}^{-6}}\]

B)                        \[3.68\times {{10}^{-6}}\]            

C)        \[3.88\times {{10}^{6}}\]        

D)        \[3.98\times {{10}^{8}}\]

Correct Answer: A

Solution :

  Antilog of 0.6 is            \[[{{H}^{+}}]\approx 4\times {{10}^{-6}}M\] Alternate Solution                 \[[{{H}^{+}}]={{10}^{-pH}}\] Taking log both sides \[\log [{{H}^{+}}]=-pH\log 10\] \[\log [{{H}^{+}}]=-5.4\times 1=-5.4\] \[[{{H}^{+}}]=\]antilog\[(-5.4)=\frac{1}{anti\log (5.4)}\] \[[{{H}^{+}}]=3.98\times {{10}^{-6}}M\]