Answer:
HCl
Explanation:
Phosgene (COCl₂) on reaction with moisture in lungs converts into Carbon dioxide and hydrochloric acid.
COCl₂ + 2 H₂O → CO₂ + 2 HCl
The HCl produced in lungs causes problems. It reacts with alveoli proteins resulting in suffocation, coughing, eyes and throat irritation and difficulty in breathing.