Question

For comfortable working, the ___________ content should be limited to about  0.6% by volume.

(a) Oxygen

(b) Hydrogen

(c) Carbon monoxide

(d) Carbon dioxide

The question was posed to me in an internship interview.

This key question is from Types of Ventilation in division Acoustics and Ventilation of Construction & Building Materials

Answer 1

Right option is (d) Carbon dioxide

For explanation I would say: It is observed that breathing is difficult when the amount of carbon dioxide by volume is about 6% and a man loses consciousness when it reaches about 10% or so. The more the amount of carbon dioxide, the more difficult is the breathing.