A quantity of 200 mL of 0.862M HCl is mixed with 200 mL of 0.431 M  $Ba{\left(OH\right)}_2$ in a constant pressure calorimeter that has a heat capacity of  $453J{K}^{-1}$. The initial temperature of the HCl and  $Ba{\left(OH\right)}_2$ solution and calorimeter is the same and are at  ${20.48}^{0}C$. For the process the heat of neutralization for  $H^{+}\left(aq\right)+O{H}^{-}\left(aq\right)\rightleftharpoons H_{2}O\left(aq\right)$ is   $-56.2kJmo{l}^{-1}$
(assume density of mixture = 1 g / mL, specific heat of the mixture = 4.18 J/g.K)
Select correct statements(s)  

Mole of  $HCl=\frac{200\times 0.862}{1000}=0.1724mol=0.1724mol{H}^{+}$
Moles of  $Ba{\left(OH\right)}_2=\frac{200\times 0.431}{1000}=0.0862mol$
Moles of  $\left(O{H}^{-}\right)=2\times \frac{200\times 0.431}{1000}=0.1724mol\left(O{H}^{-}\right)$
Thus, moles of  $H^{+}=$ moles of  $O{H}^{-}$
This is complete reaction of $HCl$  and  $Ba{\left(OH\right)}_2$.
Hence, (C) and (D) are incorrect.
Hence, enthalpy charge of reaction of $HCl$  and  $Ba{\left(OH\right)}_2$.
              $=-56.2\times 0.1724=-9.69kJ$                     
Thus, (A) is correct.
$\Delta H_{calorimeter}=C_p\Delta T$
$\Delta H_{calorimeter}=435J{K}^{-1}(T-293.48)K=0.435(T-293.48)kJ$
                             Total volume of solution = 400 mL
                             Assume density  $=1g{L}^{-1}$
Hence,                    $400mL=400g$ solutions
$\Delta H_{solution}=400g\times 4.184J{g}^{-1}{K}^{-1}(T-293.48)$
                   $=0.400\times 4.148(T-293.48)kJ$
$\Delta H_{reaction}=-(\Delta H_{reaction}+\Delta H_{cal})--9.69=[0.400\times 4.148+0.435][T-293.48]$$T=298.07Kor(298.07-273)=25.07°C$
Thus, (B) is correct