GATE ES kind:question PYQs & Answers — Page 26 — Exam Papers

Questions 251–260 of 390. Imported answers require independent review unless marked reviewed.

Topic practice 390 questionsPage 26 of 39

A flask (100 ml volume) has wastewater, which has 0.12 mg/L geosmin. Activated carbon is added in this flask for absorbing geosmin as per the Freundlich isotherm model (

where Q is mg adsorbate/mg adsorbent and C is the equilibrium concentration in mg/L). Activated carbon to be added in this flask for getting final remaining geosmin concentration of 0.05 mg/L would be ________________ (in mg/L, rounded off to three decimal places).

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A pipeline is designed to deliver 20 L/s of an oil (kinematic viscosity =

m

/s and specific gravity = 0.9) under the laminar flow condition. The minimum diameter of the pipe will be __________ (in m, rounded off to two decimal places).

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You are doing an experiment to find out BOD

of a wastewater. You have taken 25 mL wastewater having ultimate BOD of 75 mg/L and placed it in 300 mL BOD bottle and filled it with dilution water. The initial DO of the diluted sample is 6.5 mg/L. On the 5th day, you were not able to measure the DO due to some unavoidable circumstances. However, the DO at the end of the 7th day is found to be 1.25 mg/L. Assume all the experiments are done at the same temperature, and no biodegradable organics are present in the dilution water. The BOD

of the wastewater sample is ____________ (in mg/L, rounded off to two decimal places).

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In a 30 m³ room, a stove in operation consumes wood at the rate of 0.25 kg/h. The inflow and outflow rate of air in the room is the same, i.e. 500 m³/h. This stove emits a VOC species at a rate of 0.2 g/kg-wood. The VOC species gets converted to CO₂ at a rate of 0.4 per hour. Given: (i) the air in the room is completely mixed, (ii) initial concentration of the VOC species in the room is negligible, and (iii) concentration of the VOC species in the air entering the room is negligible. The concentration of the VOC species due to two hours of stove operation in the room is __________(in μg/m³, rounded off to one decimal place).

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A city generates on average 1000 metric tonnes/day of municipal solid waste and follows integrated waste management system. 15% of the total waste is recycled, 40% of the total waste is used to produce compost. 25% of the total waste is converted to refuse derived fuel (RDF) with 80% efficiency. Remaining is disposed of in a sanitary landfill. The calorific value of the RDF is 15 MJ/kg, which is further used to generate electricity. The electrical energy that could be generated from the RDF with a thermal to electrical energy conversion efficiency of 20% is ______________(in MWh/d, rounded off to two decimal places).

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An industry with an effective stack height of 80 m emits 1200 g/h of CO. The windrose plotted using the meteorological data at the top of the stack, and the relation between dispersion coefficients and wind direction are given below:

Diagram for Environmental Science and Engineering question 61

Wind Direction	Dispersion coefficients (in m): Crosswind direction	Dispersion coefficients (in m): Vertical direction
Northeast	50	20
North	45	30
Northwest	40	35
East	45	30
Southeast	55	35
South	60	40
Southwest	65	45
West	70	50

During the maximum duration of the year, the ground level PM₂.₅ concentration at the downwind distance of 2 km (at the plume centerline) from the stack is __________________ (in μg/m³, rounded off to two decimal places).

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Ms. Anita uses a BS-IV two wheeler petrol scooter, with a mileage of 50 km/L, to travel 30 km every day. She changes this two wheeler with an electric scooter, which consumes electricity at 0.1 kWh/10 km. Assuming the cost of petrol and electricity are fixed at Rs. 90 per L and Rs. 3.5 per kWh, respectively, and maintenance cost of both BS-IV two wheeler and electric scooter is negligible, the operational cost saved in a year by Ms. Anita is __________(in Rs., in integer).

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Ultimate analysis of a municipal solid waste sample is given below:

Percent by weight
Carbon	Hydrogen	Oxygen	Nitrogen	Ash
48	6	35	6	5

For 1 kg of the municipal solid waste burnt, assuming that air contains only nitrogen and oxygen, maximum CO₂ emitted is ______________(in kg, rounded off to three decimal places).

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An adult of 65 kg weight and life span of 65 years drinks water for 5 years, which is contaminated with toluene of concentration 0.15 mg/L. For toluene, reference dose is 0.200 mg/kg-d. The person drinks 2 L of water per day. The hazard quotient from the toluene exposure for the adult will be ____________(rounded off to three decimal places).

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An aeration tank needs to be installed for the removal of VOC from water, where the required rate of flow of water through the aeration tank is 180,000 m³/d. Permissible limit of VOC in the water is 12 μg/L. The saturation concentration of VOC is 5 μg/L and gas transfer rate constant is 0.40 per second at 25 °C. The initial concentration of VOC in the water is 33 μg/L. The volume of the aeration tank to satisfy the permissible limit of VOC at 25 °C is ________________(in m³, rounded off to two decimal places).

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