Answer
$V=30.59ml$
Work Step by Step
Considering stoichiometric coefficients, the amount of hydrochloric acid necessary for the reaction is twice the amount of magnesium oxide. Therefore,
$n(HCl)=2n(MgO)=2\times \frac{m(MgO)}{M(MgO)}=2\times \frac{0.104 g}{40\frac{g}{mol}}=0.0052 mol$
Volume can be easily obtained knowing the concentration of the solution:
$V(HCl)=\frac{n(HCl)}{c(HCl)}=\frac{0.0052mol}{0.17\frac{mol}{dm^3}}=0.03059dm^3=30.59ml$
This corresponds to the volume of fresh gastric juice, since its acidity corresponds to the acidity of $0.17M HCl$ solution.
