Your Answer : (Not Answered)

Correct Answer : B

These organisms are important in Vermicomposting.

Eisenia fetida (the red wiggler), Lumbricus rubellus (the red earthworm) and Eudrilus eugeniae (the African nightcrawler) are surface-dwelling earthworms that feed on decaying organic matter and breed quickly. They are the standard species for converting kitchen, farm and market waste into vermicompost, a nutrient-rich organic manure.

Nitrogen fixation is done by bacteria such as Rhizobium and Azotobacter, phosphate solubilisation by bacteria and fungi such as Bacillus and Aspergillus, and insect biocontrol by agents such as Bacillus thuringiensis or parasitoid wasps. Earthworms do none of these.

Your Answer : (Not Answered)

Correct Answer : D

The ecofriendly process is conversion into compost, biogas or bioethanol.

Composting, anaerobic digestion to biogas and fermentation to bioethanol turn the biodegradable part of solid waste into useful products: soil conditioner, fuel gas and liquid fuel. They recover resources, reduce the waste sent to landfills and cut methane released from rotting waste in dumps.

Open dumping pollutes soil, water and air and breeds disease. Landfilling takes land and can leak leachate and methane. Incineration reduces volume but releases flue gases, dioxins and ash that need careful control. None of them is the ecofriendly choice the question asks for.

Your Answer : (Not Answered)

Correct Answer : C

The match is a-iv, b-iii, c-ii, d-i.

• Sanitary landfill: burying waste below the earth's surface in engineered, lined cells covered with soil.
• Incineration: burning waste at high temperature.
• Recycling: converting waste into usable items.
• Sedimentation: removal of the larger, settleable particles from water.

Option B also starts with landfill as burying, but it pairs incineration with removal of particles and recycling with burning, which are wrong. Options A and D get landfill wrong as well.

Your Answer : (Not Answered)

Correct Answer : D

Mechanical recovery reclaims metals.

In a materials recovery facility, mixed solid waste is shredded and passed through machines that sort it by physical properties. Magnetic separators pull out ferrous metals such as steel cans, and eddy current separators throw out non-ferrous metals such as aluminium. Metals are the component most easily and profitably recovered this way.

Food waste and leaves and plant debris are biodegradable; they are recovered by biological processing such as composting or anaerobic digestion, not by mechanical separation. Plastics can be sorted, but their many types make mechanical recovery much less effective than for metals.

Your Answer : (Not Answered)

Correct Answer : B

Contaminated recyclable waste goes in the red container.

The Bio-Medical Waste Management Rules, 2016 use four colour categories. Red bags or containers are for contaminated recyclable waste such as tubing, bottles, intravenous sets, catheters, syringes without needles and gloves, which is autoclaved or treated and then recycled.

Yellow is for anatomical, soiled and chemical waste that is incinerated; white (translucent, puncture-proof) containers are for sharps such as needles; and blue is for glassware and metallic implants.

Your Answer : (Not Answered)

Correct Answer : A

The yellow container takes human anatomical, animal, microbiology and biotechnology wastes.

The Bio-Medical Waste Management Rules, 2016 sort waste into four colour categories. Yellow is for waste that is incinerated or otherwise destroyed: human anatomical waste, animal anatomical waste, soiled waste, expired medicines, chemical waste, and microbiology, biotechnology and other clinical laboratory waste.

Waste sharps such as needles and blades go in a white translucent puncture-proof container. Glassware goes in a blue container. Chemical liquid waste is listed in the yellow category but is drained through a separate collection system to an effluent treatment plant, not put in a yellow container, so liquid waste is not the answer.

Your Answer : (Not Answered)

Correct Answer : A

When the C : N ratio is too narrow, nitrogen in the compost is lost as ammonia.

Composting microbes need carbon for energy and nitrogen for protein, in a ratio of roughly 25-35 to 1 at the start. If there is too little carbon for the nitrogen present (a narrow ratio, as in fresh manure or green waste alone), the microbes cannot use all the nitrogen, and the surplus is released as ammonia gas. That causes odour and robs the finished compost of nutrient value.

A wide ratio, too much carbon, is what slows or protracts composting. The other two options describe no recognised effect of the C : N ratio.