The pair whose both species are used in acid medicinal preparation is:

Options

A. `NaHCO_(3) and Mg(OH)_(2)`
B. `Na_(2)CO_(3) and Ca(HCO_(3))_(2)`
C. `Ca(HCO_(3))_(2) and Mg(OH)_(2)`
D. `Ca(OH)_(2) and NaHCO_(3)`

Explanation

To solve the question, "The pair whose both species are used in acid medicinal preparation is:", we need to analyze the options provided and identify which pair contains both species that are commonly used in antacid preparations.

### Step-by-Step Solution:

1. **Understand the Role of Antacids**:
- Antacids are substances that neutralize stomach acidity. They are commonly used to relieve symptoms of heartburn, indigestion, and upset stomach.

2. **Identify Common Antacid Ingredients**:
- Common ingredients in antacids include sodium compounds (like sodium bicarbonate), magnesium compounds (like magnesium hydroxide), and aluminum compounds (like aluminum hydroxide).

3. **Analyze Each Option**:
- **Option 1: Sodium carbonate and magnesium hydroxide**: Both are used in antacid preparations. Sodium carbonate can neutralize acid, and magnesium hydroxide is a well-known antacid.
- **Option 2: Sodium carbonate and calcium hydroxide**: Sodium carbonate is an antacid, but calcium hydroxide is not commonly used for this purpose.
- **Option 3: Calcium bicarbonate**: This is not typically used as an antacid.
- **Option 4: Calcium bicarbonate and magnesium hydroxide**: Calcium bicarbonate is not commonly used, although magnesium hydroxide is.
- **Option 5: Calcium hydroxide and sodium bicarbonate**: Sodium bicarbonate is an antacid, but calcium hydroxide is not primarily used for this purpose.

4. **Conclusion**:
- The correct answer is **Option 1: Sodium carbonate and magnesium hydroxide**. Both species are used in acid medicinal preparation (antacids).

### Final Answer:
**The pair whose both species are used in acid medicinal preparation is: Sodium carbonate and magnesium hydroxide.**

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