Answer:
0.03429 mole
Step-by-step explanation:
The type of acid present in the stomach is hydrochloric acid (HCl).
From the balanced equation:

2 moles of HCl requires 1 mole of Mg(OH)2 fro complete neutralization.
moles of Mg(OH)2 present in 1g = mass/molar mass
= 1/58.33 = 0.01714 mole
If 1 mole of Mg(OH)2 is needed for 2 moles of HCl, then
0.01714 mole of Mg(OH)2 will require: 2 x 0.01714 moles HCl
= 0.03429 mole of HCl
Hence, 0.03429 mole of stomach acid can be neutralized by 1.00g of Mg(OH)2