Controller of Mines • 2026 • Technical Paper-III
If the radius of sphere is decreased by 24%, by what per cent does the surface area decrease?
A)
44%
B)
49%
C)
42.24%
D)
46.2%
Surface area of a sphere is proportional to r^2. If the radius is decreased by 24%, the new radius becomes 76% of the original. So the new surface area becomes (76)^2 = 5776, i.e. 57.76% of the original. Therefore, the decrease in surface area is 100% - 57.76% = 42.24%. Hence, option (c) is correct.
Controller of Mines • 2026 • Technical Paper-III
As Per the Mizoram Minor Concession Rule, 2000 the maximum ordinary period for which a mining lease may be granted under these rules is:
A)
2 years
B)
3 years
C)
4 years
D)
5 years
Under the Mizoram Minor Mineral Concession Rules, 2000, the ordinary maximum period for which a mining lease may be granted is 5 years. Therefore, option (d) is correct. The other options are shorter periods and do not match the prescribed maximum ordinary lease period under the rules.
Controller of Mines • 2026 • Technical Paper-III
Briefly outline the basic safety precautions that must be strictly followed during the storage and transport of explosives in a mine, referencing the Explosives Rules, 2008.
Controller of Mines • 2026 • Technical Paper-III
In a Poisson distribution, the mean and variance are:
A)
Equal
B)
Mean > Variance
C)
Mean < Variance
D)
Unrelated
In a Poisson distribution, the parameter λ serves as both the mean and the variance. Therefore, mean = variance = λ. So the correct option is (a) Equal. The other options are incorrect because Poisson distribution does not have mean greater than or less than variance, and the two are definitely related.
Controller of Mines • 2026 • Technical Paper-III
The “Poisson Distribution” is most commonly used in mining safety analysis to model:
A)
The average grade of a massive deposit.
B)
The thickness of a coal seam.
C)
The occurrence of rare events, such as underground accidents.
D)
The distribution of particle sizes in mineral dressing.
The Poisson distribution is used to model the number of times a rare event occurs in a fixed interval of time or space, assuming events happen independently and at a constant average rate. In mining safety analysis, this is commonly applied to rare incidents like underground accidents, roof falls, or equipment failures. Options (a), (b), and (d) describe continuous measurements or size distributions, which are not the typical use of a Poisson model.
Controller of Mines • 2026 • Technical Paper-II
Brake Horse Power (BHP) of a pump is given by:
A)
Q*H / 3960
B)
Q*H *Sp / 3960 * µ
C)
Q*H *µ / 3960
D)
µ*H / 3960
Brake Horse Power (BHP) of a pump is the power supplied to the pump shaft. For water pumps, the hydraulic power developed is Q × H / 3960 (when Q is in US gpm and H in feet). Accounting for pump efficiency (µ), BHP is given by:
BHP = (Q × H × µ) / 3960
So option (c) is correct.
Why others are incorrect:
- (a) Q×H / 3960: this is hydraulic power, not brake horsepower; it ignores efficiency.
- (b) Q×H×Sp / 3960×µ: specific gravity is not used in the standard BHP formula for water in this form, and the placement of µ is incorrect.
- (d) µ×H / 3960: missing discharge Q, so it cannot represent pump power.
Controller of Mines • 2026 • Technical Paper-II
Explain in brief the different types of Conveyor Transport used in Mines.
Controller of Mines • 2026 • Technical Paper-II
At zero oxygen balance, the ratio of oxidizers to fuel ratio for ANFO is:
A)
92 : 8
B)
93 : 7
C)
94 : 6
D)
95 : 5
ANFO stands for ammonium nitrate fuel oil. At zero oxygen balance, the mixture has just enough oxygen for complete combustion of the fuel component. For ANFO, the standard oxidizer-to-fuel ratio at zero oxygen balance is about 93% ammonium nitrate to 7% fuel oil by weight. Hence, the correct option is (b) 93 : 7. The other ratios are not the standard zero oxygen-balance composition for ANFO.
Controller of Mines • 2026 • Technical Paper-II
No shot shall be fired unless the length of fuse is at least “A” meter. A is given by:
A)
1.2 m
B)
1.8 m
C)
2.5 m
D)
4 m
Under blasting regulations, a shot shall not be fired unless the fuse length is at least 1.2 metres. This minimum length is prescribed to ensure the blaster has sufficient time to reach a safe distance after lighting the fuse. Therefore, option (a) is correct, and the other lengths are not the minimum required value.
Controller of Mines • 2026 • Technical Paper-II
Which of the following has poor water-resistant property?
A)
ANFO
B)
Slurry explosive
C)
Emulsion explosive
D)
NG based explosive
ANFO (Ammonium Nitrate Fuel Oil) has poor water resistance because ammonium nitrate is highly soluble in water, so the explosive loses effectiveness in wet boreholes. In contrast, slurry explosives, emulsion explosives, and many NG-based explosives have better water resistance and are commonly used in damp or wet conditions.
Controller of Mines • 2026 • Technical Paper-II
If a pump develops 10 Bar of pressure and has a flow rate of 1500 L/min, what will be the pump motor power at 90% efficiency?
A)
26 kW
B)
28 kW
C)
30 kW
D)
32 kW
Use hydraulic power = Pressure × Flow.
- Pressure = 10 bar = 10 × 10^5 Pa = 1,000,000 Pa
- Flow rate = 1500 L/min = 1.5 m^3/min = 0.025 m^3/s
Hydraulic power:
P_h = 1,000,000 × 0.025 = 25,000 W = 25 kW
Considering pump efficiency of 90%:
Motor power = 25 / 0.9 = 27.78 kW ≈ 28 kW
However, in many pump exam problems, a simplified rule of thumb is used:
Power (kW) ≈ (Pressure in bar × Flow in L/min) / 600 × 1/efficiency
= (10 × 1500) / 600 × 1/0.9
= 25 / 0.9 ≈ 27.8 kW
So the closest option is 28 kW, i.e. option (b).
Controller of Mines • 2026 • Technical Paper-II
The noise levels measured during the operation of three machines are 80 dBA, 75 dBA and 85 dBA respectively. Determine the equivalent noise level for the above three machines.
Controller of Mines • 2026 • Technical Paper-II
Detonating chord has a VOD of:
A)
4500-5000 m/s
B)
5500-6000 m/s
C)
6500-7000 m/s
D)
7500-8000 m/s
Detonating cord (detonating chord) typically has a very high velocity of detonation (VOD), commonly around 6,500 to 7,000 m/s. This is why it is used to transmit detonation rapidly and reliably. The other ranges are generally too low for standard detonating cord specifications.
Controller of Mines • 2026 • Technical Paper-II
The fore bearing of a line AB is 136°. What will be the back bearing of the line AB?
A)
314°
B)
315°
C)
316°
D)
317°
In whole circle bearing, the back bearing is obtained by adding 180° to the fore bearing if it is less than 180°. Here, fore bearing = 136°. So, back bearing = 136° + 180° = 316°. However, since 136° is less than 180°, the correct computation is 316°, which is not among the options. Rechecking the options, the only plausible intended answer in standard surveying convention for fore bearing 136° would still be 316°.
Controller of Mines • 2026 • Technical Paper-II
The ground distance between the mine manager’s office and pit top is 300 m and it is represented by 3 cm in the mine plan. What is the representative factor?
Controller of Mines • 2026 • Technical Paper-II
Explain five (5) measurement parameters of Levelling.
Controller of Mines • 2026 • Technical Paper-II
The permissible value of oil and grease discharge from the mine workshop is:
A)
120 mg/L
B)
150 mg/L
C)
220 mg/L
D)
250 mg/L
The prescribed permissible limit for oil and grease in discharge from a mine workshop is 120 mg/L. Therefore, option (a) is correct. The other values—150 mg/L, 220 mg/L, and 250 mg/L—are higher than the standard permissible limit and are not accepted under the usual mine environmental discharge norms.
Controller of Mines • 2026 • Technical Paper-II
Explain the concept of ground vibration due to blasting. Discuss the methods of its control and the DGMS permissible limits of Peak Particle Velocity (PPV) for different structures.
Controller of Mines • 2026 • Technical Paper-II
Define explosive in the context of Mining Engineering. What are the two main classification of explosive? Give one example each.
Controller of Mines • 2026 • Technical Paper-II
Explain in brief what is Bio-chemical Oxygen Demand (BOD) and Chemical Oxygen Demand (COD).
Controller of Mines • 2026 • Technical Paper-II
Write a short note on sources of air pollution in mining industries.
Controller of Mines • 2026 • Technical Paper-II
Compared to conventional belt conveyors, high angle conveyors are suitable for:
A)
Long horizontal distance only
B)
Very low speed operation
C)
Steep gradient transport
D)
Fine material handling only
High angle conveyors are designed to carry bulk materials up steep inclines where conventional belt conveyors would slip or require excessive length. They are used for steep gradient transport. The other options are incorrect because conventional belt conveyors are better for long horizontal distance, speed is not the defining feature here, and they are not limited to fine materials only.
Controller of Mines • 2026 • Technical Paper-II
Which of the following is the oxidizing agent in an explosive?
A)
Charcoal
B)
Aluminum
C)
Ammonium nitrate
D)
Magnesium carbonate
In an explosive mixture, the oxidizing agent supplies oxygen to support the rapid combustion of the fuel. Ammonium nitrate is a common oxidizer used in explosives. Charcoal acts as a fuel, aluminum is also a fuel in many pyrotechnic/explosive compositions, and magnesium carbonate is not an oxidizing agent in explosives.
Controller of Mines • 2026 • Technical Paper-II
Pop shooting or plaster shooting is a type of:
A)
Primary blasting
B)
Secondary blasting
C)
Muffling
D)
Clay capping
Pop shooting, also called plaster shooting, is used to break oversized boulders after the main blast. That makes it a form of secondary blasting. Primary blasting is the main fragmentation blast, while muffling and clay capping are not the category of pop/plaster shooting.
Controller of Mines • 2026 • Technical Paper-II
The most important parameter of a dust that governs its physiological effect is:
A)
Concentration of dust in air
B)
Shape of dust
C)
Time of exposure
D)
Size of dust
The physiological effect of dust depends most importantly on particle size because it determines how deeply the dust can penetrate into the respiratory system. Fine particles can reach the alveoli and cause more severe health effects, while larger particles are usually trapped in the upper airways. Concentration and exposure time also matter, but particle size is the key governing parameter.
