GATE ES 2023 Paper 1 — page 20

Complete GATE ES 2023 Paper 1 overview, original pages and practice · Timed previous-paper practice

Questions 58–60 of 65. Imported answers require review unless explicitly marked reviewed.

Paper practice 65 questionsPage 20 of 22

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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2023 · Paper 1

Question 58

Question 59

Question 60