Đáp án đúng: A
37,2 hoặc 49,6.
Nhìn các đáp án thấy tất cả đều có hai trường hợp và $\displaystyle \left\{ \begin{array}{l}\sum{{{\text{n}}_{{{\text{H}}^{\text{+}}}}}\text{=}\,\text{0,5+1}\,\text{=}\,\text{1,5}}\\\text{n}_{\text{A}{{\text{l}}_{\text{2}}}{{\text{O}}_{\text{3}}}\,\,\text{(X)}}^{{}}\text{=}\,\text{0,01}\text{.5}\,\text{=}\,\text{0,05}\end{array} \right.$
Nếu Axit dư
$\displaystyle \begin{array}{l}\text{n}_{\text{A}{{\text{l}}_{\text{2}}}{{\text{O}}_{\text{3}}}}^{\text{X}}\text{=}\,\text{0,01}\text{.5}\,\text{=}\,\text{0,05}\,\Rightarrow \,{{\text{n}}_{\text{O}}}\text{=0,15}\xrightarrow{\text{BTNT}\text{.oxi}}{{\text{n}}_{{{\text{H}}_{\text{2}}}\text{O}}}\text{=}\,\text{0,15}\,\Rightarrow \,\text{n}_{{{\text{H}}^{\text{+}}}}^{\text{du}}\text{=}\,\text{0,3}\\\xrightarrow{{}}\text{n}_{{{\text{H}}^{\text{+}}}}^{\text{pu}}\text{=}\,{{\text{n}}_{\text{O}{{\text{H}}^{\text{-}}}}}\text{=}\,\text{1,5-0,3}\,\text{=}\,\text{1,2}\xrightarrow{\text{BT}\text{.mol}\text{.ion}}\text{m}\,\text{=}\,\text{37,2}\left\{ \begin{array}{l}\text{K:0,6}\\\text{Na:0,6}\end{array} \right.\end{array}$
Có đáp án A nên ta không cần thử trường hợp OH dư nữa
