Acid | \[{{K}_{a}}\] |
HCN | \[6.2\times {{10}^{-10}}\] |
HF | \[7.2\times {{10}^{-4}}\] |
\[HN{{O}_{2}}\] | \[4.0\times {{10}^{-4}}\] |
A) \[{{F}^{-}}<C{{N}^{-}}<NO_{2}^{-}\]
B) \[NO_{2}^{-}<C{{N}^{-}}<{{F}^{-}}\]
C) \[{{F}^{-}}<NO_{2}^{-}<C{{N}^{-}}\]
D) \[NO_{2}^{-}<{{F}^{-}}<C{{N}^{-}}\]
Correct Answer: C
Solution :
[c] Higher the value of \[{{K}_{a}}\] lower will be the value of \[p{{K}_{a}}\]i.e. higher will be the acidic nature. Further since \[C{{N}^{-}},\]\[{{F}^{-}}\] and \[N{{O}_{2}}^{-}\] are conjugate base of the acids HCN, HF and\[HN{{O}_{2}}\] respectively hence the correct order of base strength will be \[{{F}^{-}}<N{{O}_{2}}^{-}<C{{N}^{-}}\] (\[\therefore \] stronger the acid weaker will be its conjugate base)You need to login to perform this action.
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