Which gas reduces the oxygen carrying capacity of haemoglobin?

Explanation

**Step-by-Step Text Solution:**

1. **Understanding Hemoglobin**: Hemoglobin is a protein found in red blood cells that is responsible for transporting oxygen from the lungs to the rest of the body.

2. **Oxygen Binding**: Hemoglobin has a high affinity for oxygen, meaning it readily binds to oxygen molecules when they are present in the lungs.

3. **Competitive Inhibitors**: Some substances can interfere with the ability of hemoglobin to carry oxygen. These substances are known as competitive inhibitors. They compete with oxygen for binding sites on hemoglobin.

...