I have put resources for this style of question on my website in the past, on my website this section is in year 12 chemistry, titration questions.
Firstly,
Ca(OH)2 + 2HCl --> CaCl2 + 2H2O
Since, 8.13mL of a 0.102mol L −1 of HCl was used, we can find the number of moles of HCl using n = M*v...