← Controller of Mines
Past Questions
The net present value of Rs. 400 at the end of 5 years at 10% discount rate is
A)
Rs. 273
B)
Rs. 226
C)
Rs. 248
D)
Rs. 245
To find the Present Value (PV) of a future sum of money, we use the formula: PV = FV / (1 + r)^n, where FV is the Future Value, r is the discount rate (expressed as a decimal), and n is the number of periods.
Given data:
Future Value (FV) = Rs. 400
Discount Rate (r) = 10% = 0.10
Time Period (n) = 5 years
Calculation:
1. Calculate the discount factor: (1 + 0.10)^5 = (1.1)^5
2. (1.1)^5 = 1.61051
3. PV = 400 / 1.61051
4. PV ≈ 248.36
Rounding to the nearest whole number as per the options provided, we get Rs. 248.
Comparing with options:
(a) Rs. 273 - Incorrect
(b) Rs. 226 - Incorrect
(c) Rs. 248 - Correct
(d) Rs. 245 - Incorrect
As per Mine Rule 1955, in respect of every medical examination, the Manager of the mine concerned shall give at least ‘B’ days of prior notice in writing to the person to be examined. What is ‘B’ stand for?
A)
7 days
B)
14 days
C)
20 days
D)
30 days
According to the Mine Rules, 1955, specifically under the regulations governing the Initial Medical Examination (IME) and Periodical Medical Examination (PME) of mine employees, the Manager is responsible for ensuring that employees are notified of their scheduled medical check-ups. The rule explicitly states that the Manager of the mine concerned shall give at least 7 days of prior notice in writing to the person to be examined. This ensures that the employee is aware of the requirement and can make the necessary arrangements to attend the examination. Options b, c, and d are incorrect as they do not align with the statutory notice period specified in the Mine Rules, 1955.
If the median of noise data collected during day time within the core zone of an opencast mine is 76 dB and its mean value is 72 dB. Then, mode value of noise is
A)
75 dB
B)
84 dB
C)
88 dB
D)
90 dB
To find the mode of the noise data, we use the empirical relationship between mean, median, and mode for moderately skewed distributions. The formula is: Mode = 3(Median) - 2(Mean).
Given values:
Median = 76 dB
Mean = 72 dB
Calculation:
Mode = 3(76) - 2(72)
Mode = 228 - 144
Mode = 84 dB
Therefore, the mode value of the noise is 84 dB. Option (b) is correct. Options (a), (c), and (d) are incorrect as they do not satisfy the empirical relationship for the given mean and median.
As per the Mines Rule 1955, Welfare Officer is appointed for every mine where _________ persons are employed.
A)
100 or
According to the Mines Rules, 1955 (specifically Rule 72), every owner, agent, or manager of a mine shall appoint a Welfare Officer if the number of persons employed in the mine is 500 or more. The Welfare Officer is responsible for the welfare of the workers and acts as a liaison between the management and the employees to ensure that statutory welfare facilities are provided and maintained. While the provided option 'a' in the prompt is truncated ('100 or'), in the context of the Mines Rules 1955, the legal threshold for the mandatory appointment of a Welfare Officer is 500 persons. If the options provided in the original exam were (a) 500, (b) 250, (c) 100, (d) 1000, then '500' is the correct legal requirement.
The general requirement for the air space for storage tank and dyked enclosures as per OMR 2017 is
A)
not less than 5% of the total capacity of the tank
B)
not less than 10% of the total capacity of the tank
C)
not less than 15% of the total capacity of the tank
D)
not less than 20% of the total capacity of the tank
According to the Oil Industry Safety, Health and Environment Guidelines (often referred to in the context of OMR - Oil Mines Regulations or related safety standards for storage), storage tanks must not be filled to their absolute brim to allow for thermal expansion of the liquid and to prevent overfilling. The standard safety requirement for the 'ullage' or air space (vapor space) in storage tanks and the capacity of dyked enclosures (bunds) is designed to contain the volume of the largest tank plus a margin for rainwater and expansion. Specifically, for the air space within the tank to prevent overflow during filling or expansion, a minimum of 10% of the total capacity is generally mandated as the safety buffer. This ensures that the tank does not become hydraulically full, which could lead to structural failure or leakage.
Which method in an investment appraisal method is based on the discounted cash flow?
A)
Net equity budgeting method
B)
Net present value method
C)
Net future value method
D)
All of the above
Investment appraisal methods are generally divided into two categories: Non-Discounted Cash Flow (Traditional) methods and Discounted Cash Flow (DCF) methods.
1. **Discounted Cash Flow (DCF)**: This approach recognizes the 'time value of money,' meaning a dollar today is worth more than a dollar in the future. DCF methods calculate the present value of future cash flows by applying a discount rate.
2. **Net Present Value (NPV)**: This is the quintessential DCF method. It is calculated by subtracting the initial investment (outlay) from the sum of the present values of all future cash inflows. If NPV > 0, the project is generally considered viable.
3. **Analysis of other options**:
- **Net equity budgeting method**: This is not a standard investment appraisal method based on DCF; it refers more to capital structure or financing rather than project appraisal.
- **Net future value method**: While one can calculate a future value, investment appraisal focuses on bringing future sums back to the 'present' to make a decision today. 'Net Future Value' is not a standard appraisal metric used in this context.
Therefore, the Net Present Value (NPV) method is the correct answer as it is based on the discounted cash flow principle.
The definition of coal under the Coal Mine Regulation (CMR) 2017 is
A)
All organic and inorganic substances
B)
All organic and inorganic substances including natural gas
C)
Both (a) & (b)
D)
anthracite, bituminous coal, lignite, peat and any other form of carbonaceous matter sold or marketed as coal
Under the Coal Mines Regulations (CMR) 2017, the term 'coal' is specifically defined to encompass various grades of carbonaceous materials. According to the regulations, 'coal' means anthracite, bituminous coal, lignite, peat and any other form of carbonaceous matter sold or marketed as coal.
- Option (a) and (b) are incorrect because 'coal' is an organic sedimentary rock; it does not include 'inorganic substances' (such as metals or salts) nor does it include 'natural gas' (which is a gaseous hydrocarbon, whereas coal is a solid fuel).
- Option (c) is incorrect as it relies on the incorrect definitions provided in (a) and (b).
- Option (d) accurately reflects the legal definition provided in the CMR 2017 framework to ensure all marketable forms of solid carbonaceous fuel are regulated under the same safety and operational standards.
The condition for negative skewness is
A)
mode = median = mode
B)
mode < median < mode
C)
mode > median > mode
D)
mode median mode
First, it must be noted that the options provided in the original question contain typographical errors (repeating 'mode' instead of 'mean'). In statistics, the relationship between the mean, median, and mode determines the skewness of a distribution.
1. **Symmetrical Distribution**: Mean = Median = Mode.
2. **Positive Skewness (Right-skewed)**: The tail on the right side is longer. The mean is pulled toward the tail, resulting in: Mean > Median > Mode.
3. **Negative Skewness (Left-skewed)**: The tail on the left side is longer. The mean is pulled toward the left, resulting in: Mode > Median > Mean.
Looking at the options provided, Option (c) 'mode > median > mode' is clearly a typo for 'mode > median > mean'. In the context of competitive exams, when such typos occur, the sequence of the inequality signs is the key. For negative skewness, the Mode is the largest value and the Mean is the smallest. Therefore, the sequence Mode > Median > Mean is the correct condition. Option (b) represents positive skewness (Mean > Median > Mode), and Option (a) represents a symmetrical distribution.
In tumbling mills, the ball filling ratio to vessel is
A)
60%
B)
50%
C)
40%
D)
30%
In tumbling mills (such as ball mills or rod mills), the filling ratio refers to the percentage of the mill's internal volume occupied by the grinding media (balls or rods). For optimal grinding efficiency, the mill must not be overfilled or underfilled. If the filling ratio is too high (e.g., 50-60%), the media cannot cascade or cataract effectively, leading to a 'dead zone' in the center and reduced impact energy. If it is too low (e.g., 30%), the media may slide or slip against the liner, causing excessive wear and inefficient grinding. In standard industrial practice for ball mills, the optimal filling ratio typically ranges between 35% and 45%, with 40% being the widely accepted theoretical and practical standard for maximizing the grinding rate and energy efficiency. Therefore, 40% is the most accurate answer among the given options.
Under the Mineral Concession Rules 1960, leases can be lapsed subject to the conditions of this rule where mining operations are not commenced within a period of _________ years from the date of execution of the lease.
A)
one
B)
two
C)
three
D)
five
Under the Mineral Concession Rules (MCR) 1960, specifically under the rules governing the lapse of mining leases, a lease is subject to lapsing if mining operations are not commenced within a specified timeframe. According to the standard provisions of the MCR 1960, if mining operations are not commenced within a period of two years from the date of execution of the lease, the lease can be lapsed by the appropriate authority. This ensures that mineral resources are not locked up by leaseholders who do not intend to actively develop the mine. Options a (one), c (three), and d (five) are incorrect as they do not align with the statutory timeframe prescribed in the 1960 rules for the commencement of operations to avoid lapsing.
Indian coal is difficult to wash mainly due to
A)
low specific gravity
B)
high ash content
C)
low compressive strength
D)
all of the above
Coal washing (beneficiation) relies on the ability to separate clean coal from mineral matter (ash) based on differences in density. For this process to be efficient, the coal particles must maintain their structural integrity during handling and processing.
1. **Low Compressive Strength (Correct):** Indian coals are generally characterized by low compressive strength and high friability. This means that during the washing process (crushing, screening, and agitation), the coal tends to break down into very fine particles (slimes). These fines are extremely difficult to recover using standard gravity separation methods and often result in high losses of clean coal in the tailings, making the washing process inefficient.
2. **Low Specific Gravity (Incorrect):** Low specific gravity is actually a desirable trait for washing, as it creates a wider gap between the density of the clean coal (~1.3 to 1.5) and the density of the shale/ash (~2.0 to 2.6), making separation easier.
3. **High Ash Content (Incorrect):** While Indian coal has high ash content, this is the *reason why* we wash coal, not the reason why it is *difficult* to wash. High ash content is the problem; low compressive strength is the technical barrier that makes the solution (washing) difficult to implement effectively.
Therefore, the inherent physical weakness (low compressive strength) of Indian coal leads to excessive fines generation, which is the primary technical difficulty in its beneficiation.
According to Mines Rule 1955, what should be the minimum floor area of a shelter in a mine?
A)
8 m2
B)
12 m2
C)
14 m2
D)
20 m2
Under the Mines Rules, 1955, specific standards are laid down for the provision of shelters and amenities for mine workers. According to the regulations regarding the construction and maintenance of shelters (often categorized under the welfare and safety provisions), the minimum floor area required for a shelter is specified as 12 square meters. This ensures that there is adequate space for the workers to take refuge or rest safely. Options a (8 m2), c (14 m2), and d (20 m2) do not align with the statutory minimum requirement stipulated in the 1955 Rules.
Based on the Mines Rule 1955, the initial medical examination of every person employed in the mine should be arranged within a period of ‘A’ years of the date so notified by the Manager. What is ‘A’ stand for?
A)
2
B)
3
C)
4
D)
5
According to the Mines Rules, 1955, specifically under the regulations pertaining to the medical examination of persons employed in mines, the initial medical examination (IME) is a mandatory requirement to ensure the fitness of the worker. The rules specify that the initial medical examination of every person employed in the mine should be arranged within a period of 5 years from the date so notified by the Manager. This ensures that all personnel are screened for occupational health risks and general fitness within a reasonable timeframe from the commencement of their employment or the notification of the rule. Therefore, 'A' stands for 5.
As per the Mineral Concession Rules 1960, an application for reconnaissance permit shall be made to the State Government in _________.
A)
Form ‘A’
B)
Form ‘K’
C)
Form ‘L’
D)
Form ‘M’
According to the Mineral Concession Rules (MCR), 1960, the application process for various permits and leases is standardized through specific forms. Rule 4 of the Mineral Concession Rules, 1960, explicitly states that an application for a reconnaissance permit shall be made to the State Government in Form 'A'.
Breakdown of options:
- Option (a) Form 'A': Correct. This is the prescribed form for applying for a reconnaissance permit.
- Option (b) Form 'K': Incorrect. Form 'K' is typically associated with other administrative notifications or specific reports under the rules, not the initial application for a reconnaissance permit.
- Option (c) Form 'L': Incorrect. Form 'L' is not the application form for a reconnaissance permit.
- Option (d) Form 'M': Incorrect. Form 'M' is not the application form for a reconnaissance permit.
In the Mizoram Minor Mineral Concession Rules 2000, “Dead Rent” means..
A)
Rent payable for every six month of the lease of the Minor Minerals
B)
Rent payable for every year of the lease of the Minor Minerals
C)
Rent payable for every two years of the lease of the Minor Minerals
D)
None of above
Under the Mizoram Minor Mineral Concession Rules 2000, 'Dead Rent' is a standard mining term defined as the minimum rent payable by the lessee to the government for the lease of a mineral area. This payment is mandatory regardless of whether any mineral is actually extracted from the site. In the context of these rules, Dead Rent is calculated and payable on an annual basis (per year). Therefore, option (b) is correct. Options (a) and (c) are incorrect because the statutory period for Dead Rent is annually, not semi-annually or biennially.
As per Reg.177 of MMR 1961, every fence erected on the surface shall be examined by competent person once at least in every _________ days.
A)
14
B)
7
C)
15
D)
30
According to Regulation 177 of the Metalliferous Mines Regulations (MMR), 1961, which deals with the fencing of open excavations and surface openings, it is mandatory that every fence erected on the surface to prevent persons from falling into an open cast working or a shaft/borehole must be examined by a competent person. The regulation specifically stipulates that this examination must take place at least once in every 7 days to ensure the integrity of the fence and the safety of personnel. Therefore, option (b) is the correct answer. Options (a), (c), and (d) are incorrect as they do not align with the statutory time limit prescribed in the MMR 1961.
When the particles of same or different specific gravity come to rest at differential instants, the phenomenon is termed as
A)
stratification
B)
hindered settling
C)
free settling
D)
differential acceleration
In mineral processing and sedimentation, stratification refers to the process where particles of different sizes or specific gravities settle at different rates and come to rest at different times, resulting in the formation of distinct layers (strata) based on their physical properties.
Here is why the other options are incorrect:
- b. Hindered settling: This occurs when the concentration of particles is so high that they interfere with each other's movement, slowing down the settling velocity compared to a single particle.
- c. Free settling: This is the settling of a single particle in a fluid without interference from other particles, governed by Stokes' Law or Newton's Law depending on the Reynolds number.
- d. Differential acceleration: This refers to the initial period when particles of different masses accelerate at different rates before reaching their terminal velocity; it describes the process of reaching steady state, not the final resting state in layers.
Based on CMR 2017, “Competent person” in relation to any work or any machinery, plant or equipment means a person who has attained the age of _________ and who has been duly appointed in writing by the manager as a person competent to supervise or perform that work.
A)
20
B)
25
C)
30
D)
40
According to the Coal Mines Regulations (CMR) 2017, the definition of a 'Competent Person' is specifically outlined in the definitions section. A 'Competent person' in relation to any work or any machinery, plant, or equipment is defined as a person who has attained the age of 20 years and who has been duly appointed in writing by the manager as a person competent to supervise or perform that work.
Step-by-step verification:
1. Reference: CMR 2017 Definitions.
2. Requirement 1: Age threshold. The regulations specify the minimum age as 20 years.
3. Requirement 2: Appointment. The person must be appointed in writing by the Manager.
4. Comparison with options: Option (a) 20 matches the regulatory requirement. Options (b) 25, (c) 30, and (d) 40 are incorrect as they exceed the minimum age requirement specified in the law.
The calculation of depreciation using declining-balance method
A)
ignores salvage value in determining the amount to which a constant rate is applied.
B)
multiplies a constant percentage times the previous year’s depreciation expense.
C)
yields an increasing depreciation expense each period.
D)
multiplies a declining percentage times a constant book value.
The Declining-Balance Method is an accelerated depreciation method. Here is the step-by-step analysis of the options:
1. **Analysis of Option (a):** In the declining-balance method, the depreciation rate is applied to the current Book Value (Cost minus Accumulated Depreciation) of the asset. Unlike the Straight-Line method, the salvage value is NOT subtracted from the cost to determine the depreciable base at the start. While the asset is not depreciated below its salvage value, the salvage value is ignored when calculating the annual depreciation expense. Therefore, this statement is correct.
2. **Analysis of Option (b):** This is incorrect. The constant percentage is multiplied by the current Book Value (the remaining value of the asset), not by the previous year's depreciation expense.
3. **Analysis of Option (c):** This is incorrect. Because the book value decreases every year and the rate remains constant, the depreciation expense decreases each period (it is 'declining'), not increasing.
4. **Analysis of Option (d):** This is incorrect. The method uses a constant percentage (rate) multiplied by a declining book value, not a declining percentage multiplied by a constant book value.
The monetary value of an asset decrease due to
A)
Unfavourable market conditions
B)
Wear and tear
C)
Obsolescence
D)
All of the above
Depreciation is the systematic allocation of the cost of a tangible asset over its useful life. The decrease in the monetary value of an asset can occur due to several factors:
1. Wear and Tear (Option b): This is the most common cause of depreciation. Physical deterioration occurs as an asset is used in operations (e.g., machinery parts wearing out), reducing its efficiency and value.
2. Obsolescence (Option c): An asset may lose value not because it is worn out, but because it has become outdated. This happens due to technological advancements or changes in market demand, making the existing asset less efficient or irrelevant compared to newer models.
3. Unfavourable Market Conditions (Option a): External economic factors, such as a decrease in demand for the product the asset produces or a general decline in the market value of similar assets, can lead to a decrease in the asset's monetary value (often referred to as impairment or market depreciation).
Since all three factors contribute to the reduction of an asset's monetary value, the correct answer is 'All of the above'.
The fine product from classification is known as
A)
slime
B)
slack
C)
tramp
D)
pulp
In mineral processing, classification is the process of separating particles based on their settling velocity in a fluid (usually water), which is a function of size, shape, and density.
1. **Slime (Correct):** The term 'slime' refers to the extremely fine particles (typically less than 10-20 microns) that result from the classification or grinding process. These particles are so small that they remain suspended in the fluid for a long time and are recovered as the 'overflow' or fine product of a classifier.
2. **Slack (Incorrect):** Slacks are small pieces of coal or ore that are too small to be considered 'lumps' but are larger than slimes. They are typically the result of screening rather than classification.
3. **Tramp (Incorrect):** 'Tramp iron' refers to unwanted metallic debris (like broken drill bits or bolts) that accidentally enters the processing plant and must be removed by magnets.
4. **Pulp (Incorrect):** Pulp (or slurry) is the general term for the mixture of crushed ore and water used throughout the processing circuit; it is the feed to the classifier, not the specific fine product.
The danger zone in opencast coal mines as per CMR 2017 falls within a radius of _________ meters from the place of firing of shot.
A)
500
B)
300
C)
200
D)
100
According to the Coal Mines Regulations (CMR) 2017, specifically under the regulations governing the use of explosives and blasting operations in opencast mines, the 'danger zone' is defined to ensure the safety of personnel and equipment from fly-rock and blast effects. For opencast coal mines, the danger zone is specified as the area falling within a radius of 500 meters from the place of firing of the shot. This area must be cleared of all unauthorized persons and properly guarded before the blast is initiated. Options b (300), c (200), and d (100) are incorrect as they do not meet the statutory safety distance mandated by the CMR 2017 for the danger zone in opencast mines.
For normal distribution which one of the followings statements is true?
A)
mean, median and mode will coincide
B)
mean and median coincide but they are different from mode
C)
mean, median and mode are different from each other
D)
median and mode coincide but they are different from mean
A Normal Distribution is a continuous probability distribution that is perfectly symmetrical about its center.
1. **Symmetry**: Because the distribution is symmetric, the area to the left of the center is equal to the area to the right. This means the center point is the Median (the 50th percentile).
2. **Peak**: The highest point of the bell-shaped curve represents the most frequent value, which is the Mode.
3. **Balance Point**: In a perfectly symmetric distribution, the arithmetic average (Mean) is located exactly at the center of symmetry.
Since the peak, the center of symmetry, and the 50th percentile all occur at the same point in a normal distribution, the Mean, Median, and Mode are identical (they coincide).
- Option b, c, and d are incorrect because they describe skewed distributions. In a positively skewed distribution, Mode < Median < Mean; in a negatively skewed distribution, Mean < Median < Mode.
As per the Explosive Rule, 2008 a tamping rod made entirely of _________ should be used for stemming and charging of shot hole.
A)
Wood
B)
Iron
C)
Steel
D)
all of the above
According to the Explosives Rules, 2008, and general safety standards for blasting operations in mining and quarrying, a tamping rod must be made of a non-sparking material to prevent the accidental initiation of explosives. Wood is a non-conductive and non-sparking material, making it safe for stemming (filling the top of the hole with inert material) and charging. Iron and Steel (options b and c) are ferromagnetic materials that can create frictional sparks when striking the sides of a borehole or the explosive charge itself, which could lead to a premature explosion. Therefore, only wood is the permissible material among the given options.
According to Explosive Rule, 2008 the number of shots, which explode, shall be counted and unless it is certain that all the shots have exploded no person shall approach or be permitted to approach the place until _________ minutes after the firing of shots.
A)
15
B)
20
C)
30
D)
45
According to the safety protocols outlined in the Explosives Rules, 2008 (and aligned with standard mining safety regulations such as the Coal Mines Regulations or Metalliferous Mines Regulations), there is a mandatory waiting period after blasting operations to ensure that all charges have detonated and that no 'misfires' (unexploded shots) are present. The rule specifies that the number of shots which explode shall be counted, and unless it is certain that all shots have exploded, no person shall approach or be permitted to approach the place until 30 minutes after the firing of shots. This waiting period is critical to allow for the dissipation of toxic fumes (blasting gases) and to ensure that delayed-action fuses or malfunctions do not cause accidental detonations when personnel re-enter the area. Options a (15), b (20), and d (45) are incorrect as they do not align with the statutory time limit prescribed in the rules.