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`50 ml, 0.1M NaHCO_(3)` aqueous solution is mixed with `50 ml, 0.8 M Na_(2)CO_(3)` aqueous solution at `25^(@)C`. The `pH` of resulting solution exiists between colour transition range of an indicator which is: `(K_(a_(1))=4xx10^(-7), K_(a_(2)) =2xx10^(-11) "for" H_(2)CO_(3))`A. Phenol red `(6.8 "to" 8.4)`B. Propyl red `(4.6 "to" 6.4)`C. Phenolphathalein `(8.3 "to" 10.1)`D. Malachite green `(11.4 "to" 13)` |
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Answer» Correct Answer - D Buffer solution `pH=pK_(a_(2))+log[CO_(3)^(-2)]/([HCO_(3)^(-)])=(11-log2)+log((40)/(5))` `=11+21log2 = 11.6` |
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