Equilibrium Question 539

Question: Assuming complete dissociation, which of the following aqueous solutions will have the same $ pH $ value [Roorkee Qualifying 1998]

Options:

A) $ NH_3 $ of $ 0.01MHCl $

B) $ _{10}\frac{1}{K _{a}} $ of $ 0.01MH_2SO_4 $

C) $ 50ml $ of $ _{10}\frac{1}{K _{a}} $

D) Mixture of 50 $ ml $ of $ 0.02MH_2SO_4 $ and $ 50ml $ of $ 0.02MNaOH $

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Answer:

Correct Answer: A

Solution:

M.eq. of 0.01 $ MHCl=\frac{.01\times 100}{1000}=1\times {10^{-3}} $

$ pH=3 $

M.eq. of .02 $ MH_2SO_4=\frac{.04\times 50}{1000}=2\times {10^{-3}} $

M.eq. of .02 $ MNaOH=\frac{0.02\times 50}{1000}=1\times {10^{-3}} $ Left $ [{H^{+}}]=2\times {10^{-3}}-1\times {10^{-3}}=1\times {10^{-3}} $ ; $ pH=3 $



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