The incomplete combustion of firewood in homes produce a poisonous gas 'X'. When inhaled gas 'X' combines with substance 'Y' present in blood and reduces the capacity of blood to carry gas 'Z' causing respiratory problems. Identify 'X', 'Y' and 'Z' :

Question

The incomplete combustion of firewood  in homes produce a poisonous gas 'X'.  When inhaled gas 'X' combines with  substance 'Y' present in blood and  reduces the capacity of blood to carry  gas 'Z' causing respiratory problems.  Identify 'X', 'Y' and 'Z' :

Accepted Answer

The question addresses the issue of incomplete combustion of firewood in homes, which leads to the production of a poisonous gas 'X'. This gas, when inhaled, interacts with a substance 'Y' in the blood, reducing the blood's ability to carry gas 'Z', thereby causing respiratory problems. Let's analyze why Option 3 is the correct answer.

**Explanation for Option 3:**

1. **Gas 'X' - Carbon Monoxide (CO):** Incomplete combustion of firewood often results in the production of carbon monoxide, a colorless and odorless gas. This occurs because there is not enough oxygen to convert all carbon in the wood to carbon dioxide (CO2), leading to the formation of carbon monoxide instead.

2. **Substance 'Y' - Hemoglobin:** Hemoglobin is a protein in red blood cells responsible for transporting oxygen from the lungs to the rest of the body. Carbon monoxide has a high affinity for hemoglobin, forming a compound called carboxyhemoglobin. This binding is much stronger than that of oxygen, which significantly reduces the blood's capacity to carry oxygen.

3. **Gas 'Z' - Oxygen:** Oxygen is the essential gas that hemoglobin transports throughout the body. When carbon monoxide binds to hemoglobin, it prevents oxygen from binding effectively, leading to reduced oxygen delivery to tissues and organs, causing respiratory and other systemic problems.

**Explanation for why other options are incorrect:**

1. **Option 1: Carbon Monoxide; Water; Carbonic Acid**
   - Water and carbonic acid are not involved in the process described. Carbon monoxide affects hemoglobin, not water, and carbonic acid is not a gas carried by hemoglobin.

2. **Option 2: Carbon Dioxide; Water; Carbonic Acid**
   - Carbon dioxide is a product of complete combustion, not incomplete combustion. Additionally, water and carbonic acid are not relevant to the mechanism described in the question.

3. **Option 4: Carbon Dioxide; Hemoglobin; Oxygen**
   - While hemoglobin and oxygen are correctly identified, carbon dioxide is not the gas produced by incomplete combustion. Carbon dioxide is a normal byproduct of respiration and does not cause the binding issue described with hemoglobin.

In conclusion, Option 3 correctly identifies carbon monoxide as the poisonous gas produced by incomplete combustion, hemoglobin as the substance it binds to, and oxygen as the gas whose transport is impaired, leading to respiratory issues.