Em tham khảo nha :

\(\begin{array}{l}
{C_M} = \dfrac{n}{V}\\
d = \dfrac{{{m_{{\rm{dd}}}}}}{v} \Rightarrow {m_{{\rm{dd}}}} = d \times v = \dfrac{{d \times V}}{{1000}}\\
V = 1000v\\
C\%  = \dfrac{m}{{{m_{{\rm{dd}}}}}} \times 100\%  = \dfrac{{n \times M}}{{{m_{{\rm{dd}}}}}} \times 100\% \\
 \Rightarrow {C_M} = \dfrac{{C\%  \times d \times 10}}{M} = \dfrac{{37 \times 1,19 \times 10}}{{36,5}} = 12M
\end{array}\)

Đáp án:

 C%$_{ddHCl}$ = 37% ⇒ 100g dd HCl chứa 37g HCl 

$V_{100gddHCl}$ =  $\frac{mddHCl}{D}$ = $\frac{100}{1,19}$ = 84,03 (l)

$n_{HCl(100gddHCl)}$ = $\frac{37}{36,5}$ = 1,01 (mol)

$C_{MddHCl(37phantram)}$ = $\frac{1,01.1000}{84,03}$ = 12M