Question: Sodium bicarbonate (NaHCO_{3}) will neutralize stomach acid (HCl) in a double replacement reaction as follows: NaHCO_{3} + HCl -> NaCl + CO_{2} + \Box What is the product necessary to make this reaction complete?

  Options: 
 A. 2HO
 B. HO_{2}
 C. H_{2}O_{2}
 D. H_{2}O
Answer: D