100 mL of 0.1 M ` Na_2 CO _ 3` solution is titrated with `0.1 M ` HCl solution. If reaction taking placing during titrationis
` Na _ 2 CO _ 3 + HCl to Na HCO _ 3 + NaCl`
then find pH at half equivalent point. for `H_2 CO _ 3 , Ka_ 1 = 10 ^(-7)` and `Ka _ 2 = 10 ^( -11)`.

Answer

A

Explanation

`Na_(2)CO_(3)+HCltoNaHCO_(3)+NaCl`
Meq.`" "10" "5`
`" "5" "-" "5" "5`
Resulting solution is acidic buffer solution
`pH=PKq_(2)+"log" underset([NaHCO_(3)])overset([Na_(2)CO_(3)])(to)pH=pKq_(2)=11`