Blasting is the loudest, most visible and most dangerous part of mining, and for that reason it is a favourite topic in mining exams. Examiners love asking about the types of explosives, how they are initiated, what permitted explosives are, how they are stored and what to do when a shot fails.
This is Part 1 of our Blasting and Explosives MCQ series. It covers the foundations that every other topic builds on. Try each question first, then tap Show Answer and read the short explanation.
Blasting and Explosives MCQs: Part 01
1. What is the primary purpose of blasting in mines?
- A. To ventilate the mine
- B. To break rock or coal
- C. To drain water
- D. To cool the air
Show Answer
Answer: BExplosives are used to fragment rock and coal so that it can be loaded and removed. Ventilation, drainage and cooling are done by other means.
2. Which of the following is a low explosive?
- A. Dynamite
- B. ANFO
- C. Gunpowder (black powder)
- D. PETN
Show Answer
Answer: CGunpowder burns rapidly (deflagrates) instead of detonating, which makes it a low explosive. Dynamite, ANFO and PETN are high explosives.
3. What is the term for the very fast reaction of a high explosive, in which a shock wave travels through the explosive?
- A. Detonation
- B. Deflagration
- C. Corrosion
- D. Combustion of fuel only
Show Answer
Answer: AIn detonation, a supersonic shock wave moves through the explosive and drives the reaction. In deflagration, the burning moves much more slowly.
4. ANFO is made of ammonium nitrate prills mixed with about 6 percent of:
- A. Water
- B. Sand
- C. Gunpowder
- D. Fuel oil (diesel)
Show Answer
Answer: DAmmonium nitrate is the oxidiser and fuel oil is the fuel. The mix is cheap and widely used in large blasting operations, but ANFO loses sensitivity when it gets wet.
5. The core of a detonating fuse (detonating cord) commonly contains:
- A. TNT
- B. PETN
- C. Gunpowder
- D. ANFO
Show Answer
Answer: BA detonating fuse has a core of a high explosive, most commonly PETN, wrapped in textile and plastic. It carries the detonation along the cord to the charge.
6. How does an electric detonator work?
- A. By the heat of a flame
- B. By a manual strike
- C. An electric current heats a bridge wire, which fires the ignition charge
- D. By gas pressure
Show Answer
Answer: CCurrent flowing through the bridge wire heats it and initiates the ignition mixture, which then fires the base charge.
7. Water-gel (slurry) explosives are:
- A. Mixtures of ammonium nitrate, sensitisers and water, thickened into a gel
- B. Explosives that work only underwater
- C. Nuclear explosives
- D. Types of gunpowder
Show Answer
Answer: AThe water content and gelling agents make slurries water resistant and safer to handle than many older explosives.
8. Why are permitted explosives used in gassy coal mines?
- A. They are the cheapest
- B. They are easiest to buy
- C. They produce more fumes
- D. They give a cooler, shorter flame, which reduces the risk of igniting methane or coal dust
Show Answer
Answer: DPermitted explosives are specially formulated and tested for use in gassy and dusty coal mines. Use them only as the regulations allow.
9. Where should explosives be stored?
- A. In an open yard
- B. In an approved, licensed magazine
- C. In a wooden hut
- D. In an office room
Show Answer
Answer: BExplosives must be kept in properly designed and licensed magazines, away from heat, ignition sources and unauthorised access.
10. Which test is commonly used to measure the strength of an explosive?
- A. Drop ball test
- B. Gallery test
- C. Trauzl lead block test
- D. Cage test
Show Answer
Answer: CIn the Trauzl test, a small charge is fired in a lead block, and the enlargement of the cavity shows the explosive's strength. The ballistic mortar is another method.
11. The Explosives Act in India was first enacted in:
- A. 1884
- B. 1905
- C. 1942
- D. 1952
Show Answer
Answer: AThe Explosives Act, 1884 is the main law. Detailed requirements are in the Explosives Rules, 2008 and other rules.
12. What generally happens to the sensitivity of an explosive when the temperature rises?
- A. It decreases
- B. It stays exactly the same
- C. It becomes zero
- D. It increases
Show Answer
Answer: DHeat generally makes explosives more sensitive and less stable, which is why storage temperature matters.
13. A good stemming material for a blast hole is:
- A. Wood chips
- B. Clay and sand mix, which is incombustible
- C. Coal dust
- D. Oil-soaked waste
Show Answer
Answer: BStemming confines the gases in the hole and helps the explosive do useful work. In coal mines it must be incombustible. Coal dust or oily waste is dangerous.
14. Delay detonators are used to:
- A. Fire the holes in sequence with small time gaps, to reduce vibration and improve fragmentation
- B. Make the explosive stronger
- C. Store explosives
- D. Cool the explosive
Show Answer
Answer: AFiring holes in a planned sequence reduces the charge fired at one time, which helps control ground vibration and improves the blast result.
15. In the case of a misfire, which action must be avoided?
- A. Waiting for the specified time
- B. Informing the supervisor
- C. Drilling into or digging out the misfired hole carelessly
- D. Following the approved procedure
Show Answer
Answer: CA misfire is a charge that has failed to go off. It remains dangerous. Only the approved procedure under a competent person should be followed.
Answer key
| Q | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
|---|---|---|---|---|---|---|---|---|
| Ans | B | C | A | D | B | C | A | D |
| Q | 9 | 10 | 11 | 12 | 13 | 14 | 15 | |
| Ans | B | C | A | D | B | A | C |
Quick revision: low vs high explosives
| Point | Low explosive | High explosive |
|---|---|---|
| Reaction | Deflagration (rapid burning) | Detonation (supersonic shock wave) |
| Example | Gunpowder (black powder) | Dynamite, TNT, PETN, ANFO, slurries |
| Typical use | Where a pushing, heaving action is needed | Most mining and quarry blasting |
Initiation system at a glance
- Detonators: start the explosive. They may be electric, non-electric (shock tube) or electronic, with delay options.
- Detonating fuse: carries the detonation along a cord, usually with a PETN core.
- Primer: the cartridge or booster that holds the detonator and starts the main charge.
- Stemming: incombustible material (clay and sand) used to confine the charge.
Note: these questions are for exam practice and general knowledge. They are not blasting instructions. Always work to the Explosives Rules, the Coal Mines Regulations or Metalliferous Mines Regulations, DGMS circulars and your mine's approved blasting procedures, and use only authorised, competent persons for shotfiring.
Blasting and Explosives MCQ Series
This series is designed to build a clear understanding of explosives and safe blasting and to help with exam preparation.
Next: Part 02
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