Which of the following statements are correct ?

Options

A. `OH^(-)` is a stronger base than `NH_(2)^(-)`,
B. `H_(2),O` is a stronger base than `CH_(3),OH`
C. `CH_(3),COO` is a stronger base than HCOOH
D. A Lewis acid is a compound that accepts a pair of electrons.

Answer

To determine which statements are correct, let's analyze each option step-by-step.

### Step 1: Analyze the first statement
**Statement 1:** OH⁻ is a stronger base than NH₂⁻.

- **Analysis:**
- OH⁻ (hydroxide ion) is the conjugate base of H₂O (water).
- NH₂⁻ (amide ion) is the conjugate base of NH₃ (ammonia).
- H₂O is a stronger acid than NH₃, which means that OH⁻ is a weaker base than NH₂⁻.

**Conclusion:** This statement is **incorrect**.

### Step 2: Analyze the second statement
**Statement 2:** H₂O is a stronger base than CH₃OH.

- **Analysis:**
- CH₃OH (methanol) is a stronger acid than H₂O because it has a lower pKa value.
- Therefore, the conjugate base of CH₃OH (which is CH₃O⁻) is weaker than the conjugate base of H₂O (which is OH⁻).

**Conclusion:** This statement is **incorrect**.

### Step 3: Analyze the third statement
**Statement 3:** CH₃COO⁻ is a stronger base than CH₃OH.

- **Analysis:**
- CH₃COO⁻ (acetate ion) is the conjugate base of CH₃COOH (acetic acid).
- The pKa of acetic acid is approximately 4.8, while the pKa of CH₃OH is approximately 16.
- Since acetic acid is a much stronger acid than methanol, its conjugate base (CH₃COO⁻) is a stronger base than the conjugate base of methanol (CH₃O⁻).

**Conclusion:** This statement is **correct**.

### Step 4: Analyze the fourth statement
**Statement 4:** A Lewis acid is a compound that accepts a pair of electrons.

- **Analysis:**
- By definition, a Lewis acid is indeed a substance that can accept an electron pair to form a covalent bond.

**Conclusion:** This statement is **correct**.

### Final Summary
- **Correct Statements:**
- Statement 3: CH₃COO⁻ is a stronger base than CH₃OH.
- Statement 4: A Lewis acid is a compound that accepts a pair of electrons.

- **Incorrect Statements:**
- Statement 1: OH⁻ is a stronger base than NH₂⁻.
- Statement 2: H₂O is a stronger base than CH₃OH.