Question

1. which compound is used as an antacid to neutralize excess stomach acid? a) nacl b) naoh c) mg(oh)₂ d) kcl

Explanation:

• Antacids are substances that neutralize excess stomach acid (which is acidic, mainly HCl). They are typically weak bases.
• Option a: NaCl (sodium chloride) is a salt, neutral in nature, and does not react with acid to neutralize it.
• Option b: NaOH (sodium hydroxide) is a strong base, highly corrosive, and cannot be used as an antacid as it can damage the stomach lining.
• Option c: $\ce{Mg(OH)_{2}}$ (magnesium hydroxide) is a weak base. It reacts with stomach acid (HCl) as follows: $\ce{Mg(OH)_{2} + 2HCl -> MgCl_{2} + 2H_{2}O}$, neutralizing the acid. It is commonly used in antacids.
• Option d: KCl (potassium chloride) is a salt, neutral, and does not neutralize acid.

Answer:

c) $\ce{Mg(OH)_{2}}$