GATE ES year:2023 PYQs & Answers — Page 7 — Exam Papers

Questions 61–65 of 65. Imported answers require independent review unless marked reviewed.

Topic practice 65 questionsPage 7 of 7

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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