← Controller of Mines
Past Questions — 2026
Choose the word most nearly opposite in meaning to ABSTEMIOUS:
A)
Self-indulgent
B)
Frugal
C)
Temperate
D)
Moderate
“Abstemious” means sparing and moderate, especially in eating and drinking; self-denying or restrained. The word most nearly opposite is “self-indulgent,” which means giving in to one’s desires and pleasures. The other options—“frugal,” “temperate,” and “moderate”—are close in meaning to abstemious, not opposites.
Karl Pearson’s coefficient of skewness is zero when:
A)
Mean Mode
B)
Mean = Mode
C)
Mean > Mode
D)
Mode > Mean
Karl Pearson’s coefficient of skewness is given by (Mean − Mode) / Standard Deviation. It becomes zero when the numerator is zero, i.e., when Mean = Mode. This indicates a symmetric distribution. The other options imply a non-zero difference between mean and mode, so the skewness would not be zero.
An “Exponential Distribution” is frequently used in mine reliability engineering to represent:
A)
Time between equipment failures.
B)
The shape of a blast fragment.
C)
The depth of a borehole.
D)
The market price of minerals.
The exponential distribution is commonly used in reliability engineering to model waiting times between independent random events, especially failures. In mines, it represents the time between equipment failures. The other options are unrelated: blast fragment shape is typically studied using fragmentation distributions, borehole depth is a direct measurement, and mineral market price is an economic variable.
Find the odd one out
A)
AK
B)
CM
C)
EP
D)
DN
Convert letters to positions: A=1, K=11; C=3, M=13; E=5, P=16; D=4, N=14. In (a), (b), and (c), the second letter is obtained by adding 10, 10, and 11 respectively, but more importantly the pairs follow the pattern of increasing first letters by 2: A, C, E and second letters by 2: K, M, P except the last one breaks the sequence because D does not continue the odd progression. A clearer view is that the first letters form A, C, E, D, where D is out of order and does not fit the alternating progression. Hence DN is the odd one out.
“To burn the candle at both ends” means:
A)
To be very resourceful.
B)
To waste energy on a useless project.
C)
To work or play excessively without enough rest.
D)
To light a room efficiently.
The idiom "to burn the candle at both ends" means to use up one's energy too quickly by working or socializing too much and not getting enough rest. Option (c) matches this meaning exactly. Option (a) is about resourcefulness, (b) suggests a useless project, and (d) is a literal meaning, so all are incorrect.
What is the meaning of the idiom “To tilt at windmills”?
A)
To attack imaginary enemies or grievances.
B)
To engage in agriculture.
C)
To build renewable energy sources.
D)
To behave in a strange manner.
The idiom "to tilt at windmills" comes from Don Quixote, who attacked windmills thinking they were giants. It means to fight imagined problems, enemies, or grievances rather than real ones. Option (b) is unrelated to the idiom, (c) refers to wind energy, and (d) is too vague and does not capture the specific meaning.
Which one of the following has a greater perimeter than the rest?
A)
A square with an area of 36 sq cm
B)
An equilateral triangle with a side of 9 cm
C)
A rectangle with 10 cm as length and 40 sq cm as area
D)
A circle with a radius of 4 cm
Compute the perimeter (circumference) of each figure: (a) Square area 36 sq cm, so side = 6 cm and perimeter = 4 × 6 = 24 cm. (b) Equilateral triangle side 9 cm, perimeter = 3 × 9 = 27 cm. (c) Rectangle length 10 cm, area 40 sq cm, so breadth = 40/10 = 4 cm and perimeter = 2(10 + 4) = 28 cm. (d) Circle radius 4 cm, circumference = 2πr = 8π ≈ 25.13 cm. The greatest perimeter is 28 cm, so the rectangle in option (c) has the largest perimeter. Therefore, the correct option is (c).
What sum lent out at simple interest will amount to Rs. 3400 in 3 years at 1% per month?
A)
Rs. 2400
B)
Rs. 1800
C)
Rs. 1600
D)
Rs. 2500
At simple interest, Amount = Principal + Interest.
Rate = 1% per month = 12% per year.
Time = 3 years.
So, Simple Interest = P × R × T / 100 = P × 12 × 3 / 100 = 36P / 100 = 0.36P.
Given amount = 3400,
so P + 0.36P = 3400
⇒ 1.36P = 3400
⇒ P = 3400 / 1.36 = 2500.
Thus the correct sum lent out is Rs. 2500.
Note: Among the given options, this matches option (d), not (a).
Explain the difference between Net Present Value (NPV) and Internal Rate of Return (IRR).
Under the Petroleum and Natural Gas Rules, 1959, no person shall prospect for petroleum except under:
A)
Mining Lease
B)
Reconnaissance Permit
C)
Petroleum Exploration License
D)
Prospecting Certificate
Correct option C: Petroleum Exploration License
Under Section 5 of the Explosive Substances Act, 1908, possession of explosives under suspicious circumstances may lead to imprisonment up to:
A)
5 years
B)
10 years
C)
14 years
D)
Life imprisonment.
Under Section 5 of the Explosive Substances Act, 1908, any person in possession of explosives under circumstances giving rise to a reasonable suspicion that they are intended for an unlawful object may be punished with imprisonment which may extend to 10 years, and also be liable to fine. Hence, the correct answer is 10 years. The other options are incorrect because Section 5 does not prescribe 5 years, 14 years, or life imprisonment for this offence.
100 students appeared for two examinations, 60 passed the first, 50 passed the second and 30 passed both. The probability that a student selected at random has failed in both the examination, is:
A)
0.3
B)
0.2
C)
0.4
D)
0.1
Let A = passed the first examination and B = passed the second examination. Given: |A| = 60, |B| = 50, and |A ∩ B| = 30. So, the number who passed at least one exam is |A ∪ B| = 60 + 50 - 30 = 80. Therefore, the number who failed in both exams is 100 - 80 = 20. Hence, the required probability = 20/100 = 0.2. Since the options include 0.2, the correct option is (b).
Find the odd number out in the following set: 8, 27, 64, 100, 125, 216.
A)
8
B)
27
C)
125
D)
100
The numbers 8, 27, 64, 125, and 216 are perfect cubes: 2³, 3³, 4³, 5³, and 6³. But 100 is not a cube. Therefore, 100 is the odd one out.
Which measure of central tendency is most affected by extreme values (outliers) in a sampling dataset?
A)
Median
B)
Mode
C)
Arithmetic Mean
D)
Range
The arithmetic mean uses every value in the dataset, so very large or very small outliers can pull it up or down significantly. The median is resistant to extreme values, and the mode depends only on the most frequent value. Range is not a measure of central tendency; it is a measure of dispersion.
Under National Mineral Policy, 2019, the State acts as:
A)
Absolute owner of mineral resource
B)
Regulatory authority without fiduciary role
C)
Trustee of mineral resources on behalf of the people
D)
Revenue collecting agency only
Under the National Mineral Policy, 2019, minerals are recognized as a valuable asset of the nation, and the State is expected to act as a trustee of mineral resources on behalf of the people. This reflects the public-trust approach rather than absolute ownership. So (c) is correct. Options (a), (b), and (d) are incorrect because the policy does not treat the State merely as an absolute owner, a bare regulator, or only a revenue-collecting agency.
If the “Coefficient of Variation” of ore grade in two different blocks is 15% and 30% respectively, which block has higher relative variability?
A)
The block with 15%
B)
The block with 30%
C)
Both have equal variability
D)
Coefficient of variation does not measure variability
The coefficient of variation (CV) measures relative variability: a higher CV means greater dispersion relative to the mean. Since 30% is greater than 15%, the block with 30% has higher relative variability. Option (a) is incorrect because 15% is lower variability, (c) is incorrect because the values are not equal, and (d) is incorrect because CV is specifically used to measure relative variability.
According to the Metalliferous Mines Regulations, a “Reportable Injury” means any injury which involves the enforced absence of the injured person from work for a period of:
A)
24 hours or more
B)
48 hours or more
C)
72 hours or more
D)
7 days or more
Under the Metalliferous Mines Regulations, a ‘reportable injury’ is one that causes the injured person to be absent from work for 24 hours or more. Therefore, option (a) is correct. The other options (48 hours, 72 hours, 7 days) do not match the regulatory definition.
Briefly explain the working principle of a Ball Mill. Why is it preferred for fine grinding compared to a Rod Mill?
Heavy Media Separation (HMS) is primarily based on the difference in ________ of the minerals.
Answer: specific gravity
Heavy Media Separation (HMS) separates minerals based on differences in specific gravity (relative density). In a suitable heavy medium, lighter particles float and heavier particles sink. It is not primarily based on size, shape, or magnetic property, so the correct fill is "specific gravity".
Jigging is a process of separating particles based on their density using:
A)
A constant horizontal flow of air.
B)
A vertical pulsating column of water.
C)
High-tension electrical wires.
D)
Chemical reagents.
Jigging is a gravity concentration process used in mineral processing. It separates particles mainly on the basis of density difference by applying repeated upward and downward pulsating water currents through a bed of particles. Heavier particles settle faster, while lighter particles are carried upward. Option (a) describes air flow used in some pneumatic separation methods, not jigging. Option (c) refers to electrostatic separation, and option (d) refers to flotation or chemical separation methods.
Primary crushers are mainly classified into:
A)
Jaw and Cone crusher
B)
Jaw and Gyratory crusher
C)
Roll and Hammer crusher
D)
Cone and Roll crusher
Primary crushers are the first stage of size reduction for run-of-mine ore. The commonly used primary crushers are **jaw crushers** and **gyratory crushers** because they can handle large feed sizes and very hard material.
- **Jaw crusher**: widely used for primary crushing due to simple design and high reduction ratio.
- **Gyratory crusher**: also used in primary crushing, especially for very large capacities.
Why others are incorrect:
- **Cone crusher** is generally used as a secondary or tertiary crusher, not primary.
- **Roll crusher** is usually secondary or fine crushing.
- **Hammer crusher** is mainly for softer materials and is not a standard primary crusher classification in mineral processing.
Therefore, the correct answer is **Jaw and Gyratory crusher**.
Which explosive is most commonly used in open-cast metalliferous mines due to its safety and cost-effectiveness?
A)
Dynamite
B)
Gunpowder
C)
ANFO (Ammonium Nitrate Fuel Oil)
D)
TNT
ANFO is the most commonly used explosive in open-cast metalliferous mines because it is cheap, relatively safe to handle compared with high explosives, and suitable for large-volume blasting. Dynamite and TNT are more powerful but costlier and less commonly used for routine open-pit production blasting. Gunpowder is outdated and largely unsuitable for modern metalliferous mining.
Washing is normally performed after:
A)
Grinding
B)
Flotation
C)
Primary crushing
D)
Smelting
Washing is generally a preliminary mineral processing step used to remove clay, mud, and other adhering impurities from run-of-mine ore. It is normally done after primary crushing, when the ore has been broken into smaller pieces but before finer processing stages like grinding and flotation. Grinding comes later in the flow sheet, flotation is a separate concentration process, and smelting is a metallurgical extraction step after beneficiation.
Selection of crusher is done on the basis of particle:
A)
Shape
B)
Specific gravity
C)
Size
D)
Percentage of mineral in ore
Crusher selection in mineral processing is primarily based on the size of the feed particles and the required product size. The type of crusher is chosen to achieve the desired reduction ratio and capacity for a given particle size range. Shape, specific gravity, and percentage of mineral in ore are not the main criteria for selecting a crusher.
The percentage of the mineral occurring as a free particle in the ore in relation to the total content is known as:
A)
Degree of freedom
B)
Degree of bondage
C)
Degree of liberation
D)
Degree of integration
In mineral processing, the percentage of a mineral present as free particles in an ore relative to its total content is called the degree of liberation. It indicates how completely the valuable mineral is separated from the gangue. The other options are not standard terms in this context: degree of freedom is unrelated, degree of bondage is not a mineral processing term, and degree of integration is not used for this definition.