When something goes wrong underground, what happens in the first few minutes depends on planning done long before. Methane control, refuge chambers and emergency plans are exactly what examiners like to test, and exactly what keeps people alive in real life.
This is Part 04 of our Mining Safety MCQ series, with 15 practice questions (Q46 to Q60) for GATE Mining, DGMS and Mining Sirdar aspirants. Attempt each question first, then tap Show Answer to check and read the short explanation. If you haven't done the previous set yet, start with Mining Safety MCQ Part 03.
Mining Safety MCQs: Methane Control, Refuge Chambers and Emergency Planning (Q46 to Q60)
46. Which gas is the primary cause of most mine explosions?
A. Carbon monoxide
B. Methane
C. Hydrogen
D. Nitrogen
Show Answer
Answer: B. Methane
Methane builds up in gassy workings and explodes when it meets air and an ignition source. That is why gas monitoring is taken so seriously.
47. What is the permissible limit of methane in return airways?
A. 0.5%
B. 1.0%
C. 1.25%
D. 2.0%
Show Answer
Answer: C. 1.25%
Return air carries all the gas released in the workings, so its methane level is watched closely. If it climbs past the limit, action must be taken.
48. Methane drainage in mines is usually done by:
A. Blasting
B. GOB wells / boreholes
C. Sand filling
D. Water infusion
Show Answer
Answer: B. GOB wells / boreholes
Gas is drawn off through drilled holes and pipes before it can reach the working area and the ventilation current.
49. A refuge chamber must be designed to provide life support for at least:
A. 4 hours
B. 8 hours
C. 24 hours
D. 48 hours
Show Answer
Answer: C. 24 hours
A refuge chamber is a safe place to wait when escape is cut off, so it has to keep people alive until rescue arrives.
50. In case of fire, the primary safe direction of escape is towards:
A. Return airway
B. Intake airway
C. Goaf
D. Shaft bottom
Show Answer
Answer: B. Intake airway
Fresh air flows through the intake, while the return carries smoke and fumes. Moving along the intake keeps you in clean air.
51. Which gas mixture is called "afterdamp"?
A. Methane
B. CO + CO2 mixture after an explosion
C. Oxygen
D. SO2
Show Answer
Answer: B. CO + CO2 mixture after an explosion
Afterdamp is the poisonous, oxygen-poor mixture left behind once a fire or explosion has burned out. The CO in it is the real killer.
52. An emergency response plan in mines should include:
A. Escape route plans
B. A trained rescue team
C. Mock drills
D. All of the above
Show Answer
Answer: D. All of the above
A plan only works if the routes are known, the team is trained and everyone has practised it.
53. Which organisation in India approves mine rescue standards?
A. DGMS
B. CIL
C. ISRO
D. ONGC
Show Answer
Answer: A. DGMS
The Directorate General of Mines Safety is the regulator, so it sets and approves the standards.
54. What is the main protection inside a refuge chamber?
A. Oxygen supply
B. AC system
C. Fireproof clothing
D. Safety belts
Show Answer
Answer: A. Oxygen supply
Breathable air is the first need of anyone trapped, so oxygen supply is the heart of a refuge chamber.
55. How often should mock rehearsals be conducted for emergency planning?
A. Yearly
B. Half-yearly
C. Quarterly
D. Monthly
Show Answer
Answer: C. Quarterly
Regular drills keep the response sharp and show up weaknesses in the plan before a real emergency does.
56. Flameproof apparatus in mines is used to prevent:
A. Entry of gas
B. Sparks igniting methane
C. Water leakage
D. Dust flow
Show Answer
Answer: B. Sparks igniting methane
The enclosure is built to contain any internal explosion and stop flame escaping, so a spark inside never lights the gas outside.
57. The standard distance between two main air shafts is about:
A. 100 m
B. 300 m
C. 500 m
D. 1000 m
Show Answer
Answer: C. 500 m
Keeping the two shafts apart means a single incident cannot cut off both the intake and the way out.
58. Emergency communication in mines is generally done by:
A. Mobile phones
B. Wired intercom systems
C. Cap-lamp signals
D. All of the above
Show Answer
Answer: D. All of the above
Different situations call for different methods, so mines rely on more than one means of communication.
59. Risk assessment in mines mainly focuses on:
A. Identifying hazards
B. Evaluating risks
C. Implementing controls
D. All of the above
Show Answer
Answer: D. All of the above
Good risk assessment is a full cycle: find the hazard, judge how serious it is, then put controls in place.
60. A refuge chamber is generally designed for a capacity of:
A. 2 persons
B. 5 persons
C. 10 persons
D. 20 persons
Show Answer
Answer: C. 10 persons
The chamber is sized for a working group, with enough air and supplies for everyone inside.
Quick Revision Points
- Methane is the main explosion hazard, and drainage through boreholes and GOB wells keeps it under control.
- In a fire, move along the intake airway towards fresh air.
- Afterdamp is the dangerous CO and CO2 mixture left after an explosion.
- A good emergency plan has three parts: escape routes, a trained rescue team and regular mock drills.
- Risk assessment means identifying hazards, evaluating risks and implementing controls.
That brings Part 04 to a close. A few questions a day is far better than a long session once a week. Share this with your study group and let us know your score in the comments.
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