Which of the following two reagents form silicates when react with silica `(SiO_(2))`?

Options

A. `NaCl` and `Na_(2)S`
B. `NaOH` and `Na_(2)CO_(3)`
C. `Na_(2)SO_(4)` and `NaNO_(3)`
D. `NaBr` and `NaHSO_(4)`

Explanation

To determine which of the following two reagents form silicates when they react with silica (SiO₂), we need to identify the properties of silica and the nature of the reagents provided.

### Step-by-Step Solution:

1. **Understanding Silica (SiO₂)**:
- Silica is an amphoteric oxide, meaning it can react with both acids and bases.

2. **Identifying the Nature of Reagents**:
- We need to analyze the given options to identify which ones are basic or acidic, as SiO₂ will only react with these types of reagents.

3. **Analyzing the Options**:
- **Option A**: NaCl and Na₂S
- Both are neutral salts. They do not react with SiO₂.
- **Option B**: NaOH and Na₂CO₃
- NaOH is a strong base, and Na₂CO₃ is a weak base. Both can react with SiO₂.
- **Option C**: Na₂SO₄ and NaNO₃
- Both are neutral ionic salts. They do not react with SiO₂.
- **Option D**: NaHSO₄ and NaBr
- NaHSO₄ is slightly acidic, and NaBr is neutral. They do not react with SiO₂.

4. **Reactions with Silica**:
- **NaOH + SiO₂**:
- The reaction produces sodium silicate (Na₂SiO₃) and water.
- \( \text{SiO}_2 + 2 \text{NaOH} \rightarrow \text{Na}_2\text{SiO}_3 + \text{H}_2\text{O} \)
- **Na₂CO₃ + SiO₂**:
- The reaction also produces sodium silicate (Na₂SiO₃) and carbon dioxide.
- \( \text{SiO}_2 + \text{Na}_2\text{CO}_3 \rightarrow \text{Na}_2\text{SiO}_3 + \text{CO}_2 \)

5. **Conclusion**:
- The only option that contains reagents that can react with SiO₂ to form silicates is **Option B** (NaOH and Na₂CO₃).

### Final Answer:
The two reagents that form silicates when reacting with silica (SiO₂) are **NaOH and Na₂CO₃**.