Mine Ventilation MCQs Questions & Answers

41

The percentage of inflammable gas in an u/g coal mine should not exceed

A) 0.75% in the general body of the return air of any ventilation district and 1.5% in any place of the mine B) 0.75% in the general body of the return air of any ventilation district and 1.25% in any place of the mine C) 0.5% in the general body of the return air of any ventilation district and 1.25% in any place of the mine. D) 0.5% in the general body of the return air of any ventilation district and 1.5% in any place of the mine.

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Answer & Solution

Answer: Option B

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42

A gas mixture contains CH₄, C₂H₆ and H₂ with respective concentration of 75%, 15% and 10% by volume. The lower explosibility limit of CH₄, C₂H₆ and H₂ are 5.0%, 3.3% and 4.2% respectively. The lower explosibility limit of the gas mixture, in percentage, is

A) 5.01 B) 5.36 C) 4.68 D) 4.56

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Answer & Solution

Answer: Option D

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43

The voltage range of D6 methanometer . . . . . . . .

A) 1.2 - 2.2 B) 4 - 5 C) 2.2 - 2.8 D) 3.2 - 3.8

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Answer & Solution

Answer: Option C

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44

Ascensionally ventilated coal mine inclines ideally should have a higher methane layering number when compared to descensionally ventilated inclines. The reason is

A) In ascensionally ventilated inclines density of air is higher B) Ascensionally ventilated inclines created conditions for improved turbulent mixing of methane layer C) Methane drainage is not practiced in ascensionally ventilated incline D) Descensionally ventilated incline creates conditions for improved turbulent mixing of methane layer

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Answer & Solution

Answer: Option D

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45

An air sample produces 8% CH₄ and 3% H₂. If the lower flammability of CH₄ is 5% and H₂ is 4%, what is the lower flammability of the mixture?

A) 9.50% B) 7.16% C) 4.68% D) 3.90%

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Answer & Solution

Answer: Option C

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46

Which one of the following is used as an escape apparatus in u/g coal mine?

A) Draeger BG 172 B) Pulmometer C) Any open circuit rescue apparatus D) MSA self rescuer

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Answer & Solution

Answer: Option C

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47

The fan drift pressure readings and fan quantities are measured to be 500 Pa and 65 m³/s respectively at the time when NVP aids fan pressure. On reversal, the fan delivers a quantity of 50 m³/s while acting against NVP with fan drift pressure of 600 Pa. Assuming that the NVP remains constant in both cases the total resistance of the mine in Ns²/m⁸ will be

A) 0.9487 B) 0.2750 C) 0.4105 D) 0.1635

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Answer & Solution

Answer: Option D

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48

Samples of air collected in the intake and return gate roads of an advancing long wall face show 0.25% and 0.75% CH₄, respectively. The panel has a production of 400t in an 8 hour shift when an air quantity of 18 m³/s passes through it. Then the methane emission in m³/te of coal mined is

A) 0.02 B) 0.81 C) 2.25 D) 6.48

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Answer & Solution

Answer: Option D

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49

The type of fire extinguisher that must NOT be used in case of fire in an electric substation located in an underground metal mine is

A) Multi-purpose dry chemical extinguisher B) CO₂ snow extinguisher C) Dry chemical powder extinguisher D) Foam extinguisher

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Answer & Solution

Answer: Option D

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50

The S.I. unit of barometric pressure is

A) Pa B) Mpa C) Kpa D) K

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Answer & Solution

Answer: Option C

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Mine Ventilation MCQs Questions & Answers | Mining Engineering