The GATE Grind

GATE 2024 MN – Question 12

Surface Environment, Mine Ventilation and Underground Hazards · Underground Hazards · 1 mark · Multiple choice

In a self-contained closed-circuit breathing apparatus,

  1. Exhaled air is released outside.
  2. Exhaled air is wholly absorbed inside.
  3. Separated carbon dioxide is released outside.
  4. Carbon dioxide in exhaled air is chemically absorbed.

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Show answer and explanation

Correct answer: (D) Carbon dioxide in exhaled air is chemically absorbed.

Explanation

A closed circuit recirculates breathing gas after removing carbon dioxide with an absorbent and replenishing oxygen. Thus D. It neither discards all exhaled gas as an open circuit would nor absorbs every component of that gas.

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