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Surface Environment(13)Mine Ventilation(21)Underground Hazards(15)

Surface Environment

13 Questions

GATE→2026→Surface Environment, Mine Ventilation and Underground Hazards→Surface Environment

Q1

NAT[2 Marks]

Dust particles from a blasting operation rise up in the atmosphere to a height of 500 m. The viscosity of air is $1.80 \times 10^{-5}\text{ kg m}^{-1}\text{s}^{-1}$. Assume quiescent settling. The settling time, in days, of a dust particle of $2.5\,\mu\text{m}$ diameter and $3600\text{ kg m}^{-3}$ density is

Explanation

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Q2

NAT[2 Marks]

In a biochemical oxygen demand (BOD) test, 15 ml of wastewater sample was diluted with distilled water to completely fill a 300 ml BOD bottle and incubated at $20^{\circ}\text{C}$ for 5 days. The dissolved oxygen (DO) level before and after incubation are 9.2 $\text{mg liter}^{-1}$ and 4.4 $\text{mg liter}^{-1}$, respectively. The BOD of the sample, in $\text{mg liter}^{-1}$, is

Explanation

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Q3

NAT[2 Marks]

Average noise level at a working place is 80 dB(A) for the first 10 minutes and 60 dB(A) for the next 30 minutes. The energy equivalent continuous noise level at the place for the entire period of 40 minutes, in dB(A), is (rounded off to 2 decimal places)

Explanation

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Q4

NAT[2 Marks]

A $SO_{2}$ is emitted at a rate of $20\text{ kg/s}$ from a $10\text{ km}\times10\text{ km}$ airshed in an industrial area. Wind blows at a speed of $4\text{ m/s}$ from one direction in that area. Radiation inversion restricts the mixing height to 1200 m. Neglect $SO_{2}$ concentration in the incoming air. Assuming emitted $SO_{2}$ to be conservative, the steady state $SO_{2}$ concentration in the airshed, in $\mu\text{g/m}^{3}$, is (rounded off to 2 decimal places)

Explanation

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Q5

NAT[2 Marks]

A wastewater sample has an ultimate BOD of $300\text{ mg/L}$. BOD reaction rate constant is 0.22 per day at $20^{\circ}\text{C}$. If the temperature coefficient is 1.05, the 5-day BOD at $25^{\circ}\text{C}$ in $mg/L$, is (rounded off to 2 decimal places)

Explanation

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Q6

NAT[1 Mark]

A coal washery discharges $300\text{ m}^{3}/\text{day}$ of contaminated water in a stream having a flow rate of $0.04\text{ m}^{3}/\text{s}$. The DO level of the stream and the contaminated water are $8.5\text{ mg/L}$ and $4.1\text{ mg/L}$, respectively. Neglecting temperature impact, the resultant DO, in mg/L of the stream just after mixing is

Explanation

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Q7

NAT[1 Mark]

The combined sound pressure level measured at a point in a production bench due to one dumper and one shovel is 95 dB(A). If the sound pressure level of shovel alone is 90 dB(A), the sound pressure level of the dumper alone, in dB(A), is

Explanation

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Q8

NAT[2 Marks]

Polluted air with particulate matters of diameter $50\,\mu\text{m}$ enter with a horizontal velocity of $1.0\text{ m/s}$ at a height of 0.5 m from the bottom of a dry settling chamber. The density of the particle is $2000\text{ kg/m}^{3}$ and dynamic viscosity of the air is $1.8\times 10^{-5}\text{ kg/m-s}$. Assuming streamline flow and Stoke's law, the minimum length in m, of the chamber required for settling of the particle at its bottom, is

Explanation

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Q9

MCQ[1 Mark]

The reaction products of calcium hydroxide with acidic ferruginous mine water are

(A)

FeO, $Ca^{+}$ and $H^{+}$

(B)

FeO, CaO and $H_{2}O$

(C)

FeH_{3}, $Ca^{3+}$ and $OH^{-}$

(D)

$Fe(OH)_{3}$, $Ca^{2+}$ and H_{2}O

Explanation

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Q10

NAT[2 Marks]

In a sample of groundwater, the concentration of $Ca^{2+}$ is $200\text{ mg/l}$. The corresponding calcium carbonate hardness in $\text{mg/l}$ is [rounded off to 1 decimal place]

Explanation

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Q11

NAT[2 Marks]

A thermal power station receives coal of calorific value $4000\text{ kcal/kg}$ and uses 7000 tonnes of coal every day. Assuming 860 kcal is the heat equivalent of $1.0\text{ kWh}$, for a thermal efficiency of 40% and electrical efficiency of 85% the power generation per day in MWh is [rounded off to 1 decimal place]

Explanation

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Q12

NAT[1 Mark]

At a measurement station, the air quality parameters $PM_{2.5}$, $NO_{2}$ and $O_{3}$ have the AQI sub-index values as 180, 96, and 84, respectively. The AQI for the station is

Explanation

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Q13

NAT[2 Marks]

A city is spread over an area of $20\text{ km}\times40$ km. Wind, at an average speed of 4 m/s, enters perpendicular to the 20 km long side. On a winter day the inversion layer exists over the city at a height of 100 m. PM is emitted from the city at a rate of $1\text{ kg}/\text{s}$. The steady state PM concentration in the city air, in $\mu\text{g}/\text{m}^{3}$, assuming Box model, is

Explanation

Mine Ventilation

21 Questions

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Q14

MCQ[1 Mark]

A gradually expanding duct fitted to the outlet of an exhaust fan is known as

(A)

chimney

(B)

diffuser

(C)

evasee

(D)

equivalent orifice

Explanation

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Q15

NAT[1 Mark]

In an underground mine, an airflow of $30\text{ m}^3/\text{s}$ is delivered through a circular opening having a diameter of 5 m and a length of 500 m. Assuming that there is no change in the surface characteristics, the diameter of the opening, in m, required to double the quantity of airflow at same pressure loss is

Explanation

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Q16

NAT[1 Mark]

In an underground mine atmosphere, the alcohol of a Kata thermometer took 60 s to fall from $38^{\circ}\text{C}$ to $35^{\circ}\text{C}$. The Kata factor of the thermometer is 480 milli-calories $\text{cm}^{-2}$. The Kata cooling power, in $\text{W m}^{-2}$, is

Explanation

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Q17

MCQ[2 Marks]

In an underground coal mine, the air quantities $Q_A$ and $Q_B$ pass through ventilation districts A and B, respectively, with a pressure drop of $\Delta P$ across them. The air quantity in district B is to be increased to $Q_B^{\prime}$ by installing a booster fan without affecting district A. The capacity of booster fan ($P_B$) can be expressed as

(A)

P_{B}=\Delta P(\frac{Q_{B}}{Q_{B}^{\prime}})^{2}-\Delta P

(B)

P_{B}=\Delta P(\frac{Q_{B}^{\prime}}{Q_{B}})^{2}-\Delta P

(C)

P_{B}=\Delta P-\Delta P(\frac{Q_{B}^{\prime}}{Q_{B}})^{2}

(D)

P_{B}=\Delta P+\Delta P(\frac{Q_{B}^{\prime}}{Q_{B}})^{2}

Explanation

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Q18

NAT[2 Marks]

A main mechanical ventilator installed for an underground mine develops a pressure of 25 mm wg. A natural ventilation pressure (NVP) of 15 mm wg acting in the mine aids the ventilator, and a total $500\text{ m}^3\text{min}^{-1}$ of air is circulated. Considering the same NVP aiding, the pressure required, in mm wg, to be generated by the ventilator to circulate $1000\text{ m}^3\text{min}^{-1}$ of air is

Explanation

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Q19

MCQ[1 Mark]

The figure below shows four profiles of the environmental lapse rate. Given the dry adiabatic lapse rate $=-10^{\circ}\text{C/km}$, the atmosphere is highly unstable for the profile

(A)

OP

(B)

OQ

(C)

OR

(D)

OS

Explanation

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Q20

MCQ[1 Mark]

In a depillaring face of an underground coal mine, both wet and dry bulb temperatures are $30^{\circ}\text{C}$. The relative humidity of the face environment, in percentage, is

(A)

0

(B)

30

(C)

60

(D)

100

Explanation

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Q21

MCQ[1 Mark]

Pressure head characteristic of a mine fan and a mine characteristic curves are shown in figure below: Match the points with their corresponding nomenclatures

(A)

P->1, Q->2, R->3

(B)

P->2, Q->3, R->1

(C)

P->3, Q->1, R->2

(D)

P->1, Q->3, R->2

Explanation

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Q22

NAT[1 Mark]

In a ventilation network, three airways with resistances of $4.0\text{ Ns}^{2}\text{m}^{-8}$, $6.25\text{ Ns}^{2}\text{m}^{-8}$ and $9.0\text{ Ns}^{2}\text{m}^{-8}$ are connected in parallel. The equivalent resistance of the network in $\text{Ns}^{2}\text{m}^{-8}$ is

Explanation

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Q23

MCQ[2 Marks]

A fixed quantity of air needs to be sent through a cross section, as shown in the figure. The perimeter of the cross section is 20 m. The radius (r) of the semicircle, in m, to minimize the air velocity through the section is

(A)

20/(4+\pi)

(B)

40/(4+\pi)

(C)

20/(4-\pi)

(D)

40/(4-\pi)

Explanation

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Q24

NAT[2 Marks]

In a longwall panel, air flows at a velocity of $1.2\text{ m/s}$ through a 900 m long gate road of 2.5 m height and 3 m width. The coefficient of friction is $0.022\text{ Ns}^{2}\text{m}^{-4}$. The frictional pressure drop, in Pa, between two ends of the gate road is (rounded off to 3 decimal places)

Explanation

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Q25

MCQ[1 Mark]

A rectangular mine airway of 2.0 m width and 2.5 m height has a bend with deflection of $\pi/4$ radian. If the radius of curvature of the bend is 4.0 m, the shock factor of the bend is

(A)

0.014

(B)

0.024

(C)

0.051

(D)

0.071

Explanation

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Q26

MCQ[2 Marks]

Four identical districts of a mine are ventilated with a quantity of $3500\text{ m}^{3}/\text{min}$ at a fan drift pressure of 1.15 kPa. When one of the districts is sealed off, the change in resultant resistance is $0.072\text{ Ns}^{2}\text{m}^{-8}$. If the fan is stopped, keeping a district sealed, the quantity through the mine becomes $850\text{ m}^{3}/\text{min}$. The natural ventilation pressure in Pa, is

(A)

72.12

(B)

82.28

(C)

105.56

(D)

144.56

Explanation

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Q27

NAT[2 Marks]

A rectangular face of $2.0\text{ m}\times2.5$ m dimension is blasted with 20 kg explosive in a 1000 m long drive. One kilogram of explosive produces $2200\text{ cm}^{3}$ of nitrous fumes. The face is ventilated with a duct, located 10.0 m away from the face, to dilute the fumes. The quantity of air, in $\text{m}^{3}/\text{s}$ to be circulated for reducing the concentration of nitrous fumes to 5 ppm within a period of 5 minutes, is

Explanation

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Q28

NAT[1 Mark]

To increase the resistance of a mine roadway by $1.5\text{ Ns}^{2}\text{m}^{-8}$, the size in $\text{m}^{2}$ of the regulator to be installed is [rounded off to 2 decimal places]

Explanation

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Q29

MCQ[2 Marks]

A duct of diameter 0.60 m with an exhausting fan has -97.5 mm wg static pressure behind the fan when the air flow rate is $4.0\text{ m}^{3}/\text{s}$. If an evasee with inlet to outlet area ratio of 1:4 and efficiency 60% is attached to the outlet of the fan, the static pressure of the fan in mm of wg becomes

(A)

-104.26

(B)

- 99.13

(C)

-90.73

(D)

-80.6

Explanation

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Q30

NAT[2 Marks]

A fan installed in a mine ventilation system circulates $30\text{ m}^{3}/\text{s}$ of air to two districts A and B as shown in Figure below. It is desired to increase the quantity of air by 20% in the district B using a booster fan in it. Assuming that the main fan pressure is unchanged, the pressure of the booster fan, in Pa, is [rounded off to 2 decimal places]

Explanation

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Q31

MCQ[1 Mark]

If the ambient lapse rate is higher than the dry adiabatic lapse rate, the atmosphere is

(A)

stable

(B)

neutral

(C)

unstable

(D)

strongly stable

Explanation

GATE→2022→Surface Environment, Mine Ventilation and Underground Hazards→Mine Ventilation

Q32

MCQ[1 Mark]

Identify the WRONG statement: The application of controlled air recirculation in an underground work place can

(A)

increase the air velocity at the work place

(B)

lead to increased concentration of contaminants in the work place

(C)

require the installation of an additional fan in the system

(D)

lead to overall ventilation cost savings

Explanation

GATE→2022→Surface Environment, Mine Ventilation and Underground Hazards→Mine Ventilation

Q33

NAT[2 Marks]

An underground AC plant requires the delivery of 250 US gpm (15.85 US gpm = 1.0 lps) of chilled water. For this purpose, ice-pellets at $0^{\circ}\text{C}$ temperature (latent heat of melting, 334 kJ/kg) are mixed with water at $20^{\circ}\text{C}$ (specific heat $4.18\text{ kJ}/\text{kg}^{\circ}\text{C}$) on the surface. The mixture is adiabatically transported to the underground location such that the water at $7^{\circ}\text{C}$ becomes available for the AC plant. The requirement of ice-pellets in tonne/hr to meet the design condition, is

Explanation

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Q34

NAT[2 Marks]

An intake shaft has resistance of $0.05\text{ Ns}^{2}/\text{m}^{8}$ up to a depth of 400 m. The airflow rate is $100\text{ m}^{3}/\text{s}$ and the average density is $1.2\text{ kg}/\text{m}^{3}$. A barometer reads 99.375 kPa when placed on surface. Considering acceleration due to gravity is $9.81\text{ m}/\text{s}^{2}$, the reading of the barometer at the depth of 400 m, in kPa is

Explanation

Underground Hazards

15 Questions

GATE→2026→Surface Environment, Mine Ventilation and Underground Hazards→Underground Hazards

Q35

MCQ[1 Mark]

The cobweb-like appearance in the radiograph of the lung of a miner can be diagnosed as

(A)

silicosis

(B)

asbestosis

(C)

talcosis

(D)

coal workers' pneumokoniosis

Explanation

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Q36

MCQ[1 Mark]

In firedamp explosion, the methane concentration in the stoichiometric methane-air mixture, in % by volume, is (Assume air contains 79% nitrogen and 21% oxygen, by volume).

(A)

5.4

(B)

9.5

(C)

10.8

(D)

14.8

Explanation

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Q37

NAT[2 Marks]

A closed-circuit self-contained breathing apparatus (SCBA) contains 2 liters of $O_2$ at 200 bar. If a miner consumes $O_2$ at a rate of 2 liters $\text{min}^{-1}$, the maximum duration that the apparatus can supply $O_2$, in min, is

Explanation

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Q38

MCQ[1 Mark]

The chemicals used in a foam type fire extinguisher are

(A)

NaHCO_{3} and Na_{2}SO_{4}

(B)

Al_{2}(SO_{4})_{3} and Na_{2}SO_{4}

(C)

Al_{2}(SO_{4})_{3} and Al(OH)_{3}

(D)

NaHCO_{3} and Al_{2}(SO_{4})_{3}

Explanation

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Q39

MCQ[1 Mark]

Exposure to loud impulsive noise may lead to

(A)

Nystagmus

(B)

Siderosis

(C)

Tinnitus

(D)

Stannosis

Explanation

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Q40

MCQ[1 Mark]

In a self-contained closed-circuit breathing apparatus,

(A)

the exhaled air is released outside the apparatus.

(B)

the exhaled air is wholly absorbed within the apparatus.

(C)

CO_2 is released outside the apparatus after separating from exhaled air.

(D)

CO_2 from exhaled air is absorbed with a chemical.

Explanation

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Q41

MCQ[1 Mark]

In an underground coal mine, two fatalities and three serious bodily injuries occurred during the year 2022. The average daily employment is 1100 and annual working days is 300. The severity index as per DGMS guideline for the mine is

(A)

12.32

(B)

25.58

(C)

31.21

(D)

34.63

Explanation

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Q42

NAT[2 Marks]

The data obtained from an air sample analysis of an old working in a coal mine are given. $O_{2}$ 17.15%, $CO_{2}$ 3.40%, $CH_{4}$ 2.20%, and $N_{2}$ 77.25%. Considering atmospheric air contains $O_{2}$ 20.95%, $CO_{2}$ 0.03%, and $N_{2}$ 79.02%, the percentage of blackdamp in the old working, is

Explanation

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Q43

NAT[2 Marks]

In a development coal face, 12 holes are drilled and charged with explosive. Holes are initiated with electric delay detonators connected in series. The length of a detonator lead wire is 1.5 m. The length of the blasting cable is 120 m. Resistance of each detonator = $1.48\;\Omega$, lead wire = $0.04\;\Omega/\text{m}$, blasting cable one wire = $0.009\;\Omega/\text{m}$. The total resistance of the circuit in $\Omega$, is

Explanation

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Q44

MCQ[1 Mark]

An underground coal mine experienced 5 serious injuries, 15 reportable injuries, and 25 minor injuries during 2020. If the average employment in the mine is 1200, then the total injury rate per 1000 persons employed is

(A)

54.0

(B)

20.83

(C)

37.5

(D)

60.0

Explanation

GATE→2023→Surface Environment, Mine Ventilation and Underground Hazards→Underground Hazards

Q45

MCQ[1 Mark]

As per DGMS guidelines, the risk score in Safety Management Plan for a hazard is computed as

(A)

Consequence \times Exposure

(B)

Consequence \times Exposure \times Probability

(C)

Exposure \times Probability

(D)

Consequence \times Probability

Explanation

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Q46

NAT[1 Mark]

In a panel with 50 workers, a miner typically consumes $2.5\times10^{-3}\text{ m}^{3}/\text{min}$ of oxygen. The percentage of oxygen in the intake air is 20.95%. To ensure minimum permissible oxygen in the return air as per CMR 2017 the quantity of ventilating air in $\text{m}^{3}/\text{min}$ to be supplied to the panel is [rounded off to 2 decimal places]

Explanation

GATE→2022→Surface Environment, Mine Ventilation and Underground Hazards→Underground Hazards

Q47

MCQ[1 Mark]

Which one of the following is NOT a notifiable disease as per Indian mining legislation?

(A)

Silicosis

(B)

Noise induced hearing loss

(C)

Nystagmus

(D)

Asbestosis

Explanation

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Q48

NAT[2 Marks]

The point 'A' as shown in the Coward flammability diagram represents the gas composition of a sealed-off area of a coal mine. The volume of the sealed-off area is $10000\text{ m}^3$. Inert gas is proposed to be injected into the sealed-off area so that the gas composition comes below the LEL (lower explosibility limit). The minimum volume of the inert gas required (at the same pressure as that of the sealed-off area), in $\text{m}^{3}$ is

Explanation

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Q49

NAT[2 Marks]

An underground workshop has dimensions of 8 m length, 6 m width and 4 m height. Four identical luminaires are placed at the four corners of the roof. Each luminaire is of 100 W capacity with luminous efficacy of $100\text{ lumen}/\text{W}$. Light is transmitted spherically from luminaires and there are no reflections. The illumination on the horizontal plane at the centre of the floor, in lux is

Explanation