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Which of the following is not a source of wastewater? (a) Sewers (b) Homes (c) Industries (d) Hospitals

a) Sewers The pipes through which the wastewater flows into the sewage are known as sewers, whereas, wastewater is collected into the... View Article

In a filtration, plant water is filtered using layers of (a) sand and clay. (b) clay and fine gravel. (c) sand and fine gravel. (d) sand, fine gravel and medium gravel.

(d) sand, fine gravel and medium gravel. The sand, fine gravel and the medium gravels are used to filter as they form a layer so that efficient... View Article

Which of the following is a part of inorganic impurities of the sewage? (a) Pesticides (b) Urea (c) Phosphates (d) Vegetable waste

c) Phosphates Phosphate or phosphorus is an inorganic component and hence, it is considered an inorganic impurity in sewage. Urea, pesticides,... View Article

The system of a network of pipes used for taking away wastewater from homes or public buildings to the treatment plant is known as (a) sewers. (b) sewerage. (c) transport system. (d) treatment plant.

b) Sewerage Sewerage is the system applied in buildings for discharging wastewater to the sewage. It is a network of pipes, known as sewers,... View Article

Pick from the following one chemical used to disinfect water. (a) Chlorine (b) Washing soda (c) Silica (d) Coal

a) Chlorine Chlorine is a very good oxidizer. It kill pathogens and germs by breaking their bonds. This is how it disinfects water. Chlorine... View Article

Water polluted by various human activities causes a number of water-borne diseases. Which of the following is not a waterborne disease? (a) Cholera (b) Typhoid (c) Asthma (d) Dysentry

C) Asthma Asthma is a respiratory disorder in which a patient is allergic to allergens present in air like pollen grains or dust. Cholera,... View Article

An open-drain system is a breeding place for which of the following. (a) Flies (b) Mosquitoes (c) Organisms which cause diseases (d) All of these

d) All of these Open drain systems are a breeding place for different flies, mosquitoes, and other disease causing organisms. The waste... View Article

Which of the following is/are products of wastewater treatment? (a) Biogas (b) Sludge (c) Both biogas and sludge (d) Aerator

c) Both biogas and sludge Wastewater is collected and passed through bar screens where plastic bags, sticks, cans, napkins, etc. are removed.... View Article

Sewage is mainly a (a) liquid waste. (b) solid waste. (c) gaseous waste. (d) mixture of solid and gas.

a) Liquid waste Sewage is defined as waste water due to which it is a liquid waste. Sewage is actually the wastewater that is released... View Article

Which of the following is wastewater? (a) Water trickling from a damaged tap. (b) Water coming out of a shower. (c) Water flowing in a river. (d) Water coming out of laundry.

(d) Water coming out of a laundry. Water discharged during after routine works like washing clothes, flushing toilet, cleaning utensils makes... View Article

The picture in Figure shows tree line along the sea coast on an island near the equator. As shown, the tree tops are permanently bent in one direction. Are the trees bent towards the sea or away from it? Explain.

In the coastal regions of an island near the equator, heating and cooling of air are a regular phenomenon. During the daytime, the land gets... View Article

Describe an activity to demonstrate that warm air is lighter than cool air.

The experiment to test that warm air is lighter than cool air is:- Take two paper bags of the same size. Hang the two bags in the inverted... View Article

Suggest some precautions to be taken to prevent the roof of a tin sheet from flying away during a fierce wind storm

Some precautions to prevent the roof of a tin sheet from flying away during a fierce wind storm are given below: a) We should screw it tight. The... View Article

When strong/high-speed wind blows, an umbrella held upright at times gets upturned. Explain the reason.

High speed wind passing over the umbrella creates low pressure. Therefore, the umbrella upturns high-speed winds have low pressure due to... View Article

Paheli kept an empty bottle made of plastic inside a refrigerator. After few hours, when she opened the refrigerator she found the bottle had collapsed. Explain the possible reason.

The air inside the bottle contracts due to low temperature hence the bottle collapses due to the outside pressure. When Paheli kept the closed... View Article

A flag mounted on a flag post near the sea coast flutters in the direction of sea. At what time of the day does this happen – at midnight or in the afternoon?

In this scenario, the flag will flutter in the direction of sea when it is midnight because at nighttime the sea becomes hotter than land... View Article

Figure shows a diagrammatic representation of trees in the afternoon along a sea coast. State on which side is the sea; A or B? Give reasons for your choice.

The sea is on the side ‘B’ because at the daytime the wind is coming from that side and as we know that there is sea breeze when... View Article

A flat in Mumbai with a balcony facing the sea has some clothes hung on a clothesline in the balcony. Towards which direction the clothes will be blown in the afternoon? Explain.

In the afternoon time the land gets heated much faster than sea and hence the air above the land traps heat and rises up by getting warmed and... View Article

Why is it advisable not to shut all the doors and windows during a storm?

In order to avoid the roof from getting blown away due to the low pressure created by heavy wind. Keeping the doors and windows closed helps to... View Article

To expel hot air out of the kitchen, ‘A’ has an exhaust fan fitted on the window of her kitchen and ‘B’ has a similar exhaust fan fitted on the wall near the ceiling of her kitchen. Which of the exhaust fan will expel the hot air more effectively? Explain why?

In the kitchen of 'B' ,warm air rises up and her exhaust fan is at standard height as comparison to, A. so, it will expel the hot air more... View Article

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