When Na_2CO_3aqueous solution is being titrated with hydrochloric acid {:("Column-I " , "Column-II") ,((A) " At the start of titration", (P) " Buffer solution of " HCO_3^(-) and CO_3^(-2)),((B) "Before the first equivalent point " , (Q) "Buffer solution "H_2CO_3and HCO_3^(-) ), ((C) "At the first equivalent point",( R ) "Amphiprotic anion "pH =(1//2) (p^(ka_1) +p^(Ka_2))), ((D) "Between first and second equivalent points" , (S) "Hydrolysis of "CO_3^(-2)) :}

When Na_2CO_3aqueous solution is being titrated with hydrochloric acid

1.	When Na_2CO_3aqueous solution is being titrated with hydrochloric acid {:("Column-I " , "Column-II") ,((A) " At the start of titration", (P) " Buffer solution of " HCO_3^(-) and CO_3^(-2)),((B) "Before the first equivalent point " , (Q) "Buffer solution "H_2CO_3and HCO_3^(-) ), ((C) "At the first equivalent point",( R ) "Amphiprotic anion "pH =(1//2) (p^(ka_1) +p^(Ka_2))), ((D) "Between first and second equivalent points" , (S) "Hydrolysis of "CO_3^(-2)) :}
Answer» Solution :At the START only ` CO_3^(2-) ` is present and GETS hydrolysed ` CO_3^(2-) + H^(+) to HCO_3^(-) ` until ` 1^(ST) ` equation pt, both are present i.e., buffer of ` HCO_3^(-)and CO_3^(2-) ` At Ist equation pt only`HCO_3^(-) `present amphiprotic anion after Ist eq pt, untill 2nd equation pt ` HCO_3^(-)+HCl to H_2CO_3` i.e.,buffer of `H_2CO_3 and HCO_3^(-) `