Answer:
Titration
Explanation:
The best technique which can be used to determine the number of moles of the HCl in the sample is titration.
The given amount of HCl solution must be titrated with known concentration of the base like NaOH.
The volume of NaOH required must be noted also.
According to the reaction,

At equivalence point
Moles of
= Moles of 
Considering:-
Moles of 
Thus, in this way, moles of HCl can be determined.
Cadium
Down a period, atomic radii decrease from left to right due to the increase in the number of protons and electrons across a period.