Write four species which act both as Bronsted acid as well as base. Write their corresponding conjugate acids and bases.

Explanation

To solve the question of identifying four species that act both as Bronsted acids and bases, along with their corresponding conjugate acids and bases, we can follow these steps:

### Step 1: Understand Bronsted Acid and Base
- **Bronsted Acid**: A substance that donates a proton (H⁺).
- **Bronsted Base**: A substance that accepts a proton (H⁺).

### Step 2: Identify the First Species - Water (H₂O)
- **As a Bronsted Acid**: Water can donate a proton (H⁺) to form hydroxide ion (OH⁻).
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