Question

The incomplete combustion of firewood in homes produces a very 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 and suffocation. Identify X, Y and Z.

• A. X $\to$ carbon dioxide
  Y $\to$ haemoglobin
  Z $\to$ oxygen
• B. X $\to$ carbon monoxide
  Y $\to$ haemoglobin
  Z $\to$ oxygen
• C. X $\to$ nitrogen dioxide
  Y $\to$ chloroplast
  Z $\to$ carbon dioxide
• D. X $\to$ oxygen
  Y $\to$ haemoglobin
  Z $\to$ carbon dioxide

Answer 1

The correct option is B X $\to$ carbon monoxide

Y $\to$ haemoglobin
Z $\to$ oxygen
Incomplete combustion of firewood produces carbon monoxide. It is a dangerous gas. It cannot be easily detected as it has no smell and no colour. Carbon monoxide combines with haemoglobin easier than oxygen. Therefore, once carbon monoxide combines with haemoglobin, oxygen will not have space for combination. Carbon monoxide doesn't have any benefit to humans, but it deprives the body of oxygen.