Which of the following species can acts as bronsted base as well as a Lewis base?

Options

A. `NO_(3)^(-)`,
B. `CN^(-)`
C. `NH_(3)`
D. `BF_(3)`

Answer

To determine which species can act as both a Brønsted base and a Lewis base, we need to understand the definitions of these terms:

1. **Brønsted Base**: A species that accepts protons (H⁺ ions).
2. **Lewis Base**: A species that donates an electron pair.

Now, let's analyze the options provided in the question step by step.

### Step 1: Analyze Option 1 - NO₃⁻ (Nitrate Ion)

- **Brønsted Base**: NO₃⁻ can accept a proton (H⁺) to form HNO₃ (nitric acid). Thus, it acts as a Brønsted base.
- **Lewis Base**: The nitrate ion has lone pairs of electrons that it can donate. Therefore, it can also act as a Lewis base.

**Conclusion**: NO₃⁻ is both a Brønsted base and a Lewis base.

### Step 2: Analyze Option 2 - CN⁻ (Cyanide Ion)

- **Brønsted Base**: CN⁻ can accept a proton (H⁺) to form HCN (hydrogen cyanide). Thus, it acts as a Brønsted base.
- **Lewis Base**: The cyanide ion has a lone pair of electrons that it can donate. Therefore, it can also act as a Lewis base.

**Conclusion**: CN⁻ is both a Brønsted base and a Lewis base.

### Step 3: Analyze Option 3 - NH₃ (Ammonia)

- **Brønsted Base**: NH₃ can accept a proton (H⁺) to form NH₄⁺ (ammonium ion). Thus, it acts as a Brønsted base.
- **Lewis Base**: Ammonia has a lone pair of electrons on the nitrogen atom that it can donate. Therefore, it can also act as a Lewis base.

**Conclusion**: NH₃ is both a Brønsted base and a Lewis base.

### Step 4: Analyze Option 4 - BF₃ (Boron Trifluoride)

- **Brønsted Base**: BF₃ cannot accept a proton because it is electron-deficient and does not have the ability to gain a proton. Thus, it does not act as a Brønsted base.
- **Lewis Base**: BF₃ is a Lewis acid because it can accept an electron pair, but it cannot donate an electron pair, so it does not act as a Lewis base.

**Conclusion**: BF₃ is neither a Brønsted base nor a Lewis base.

### Final Answer

The species that can act as both a Brønsted base and a Lewis base are:
- Option 1: NO₃⁻
- Option 2: CN⁻
- Option 3: NH₃