Free Pollution of Air and Water 02 Practice Test - 8th Grade 

Question 1

Identify a cleaner vehicle fuel from the given options.

A. Diesel
B. Petrol
C. CNG
D. Kerosene

SOLUTION

Solution : C

The fuels which leave a lesser amount of toxic substances and undesirable harmful exhausts after combustion are cleaner fuels.
Natural gas is lighter than air and disperses quickly when released. Therefore CNG is a cleaner vehicle fuel than kerosene, petrol and diesel and it is also safer than other fuels. 

Question 2

Which of the following describes the difference between pure air and polluted air?

A.

Polluted air contains carbon dioxide whereas pure air does not.

B.

Amount of carbon monoxide is much more in polluted air than pure air.

C. Pure air contains only oxygen gas.
D.

Amount of sulphur dioxide and nitrogen dioxide is much more in polluted air than pure air.

SOLUTION

Solution : B and D

Pure air is composed of 78% nitrogen gas, 21% oxygen gas, and 0.03% carbon dioxide. Some other gases like argon, ozone, and water vapours are also present in small quantities. When this composition of air is disturbed by the addition of harmful substances or toxic gases such as nitrogen dioxide, sulphur dioxide, carbon monoxide, and particulate matter, then the air is said to be polluted.

Question 3

In November 2016, the national capital city, New Delhi had faced a severe increase in air pollution levels which continued for more than 2 weeks. Identify the major contributor(s) to this situation from the below-given options.

A.

Vehicle emissions

B.

Airways emission

C. Burning of stubble (crop residue) in the nearby farming villages
D. Cigarette smoking

SOLUTION

Solution : A and C

Air pollution in New Delhi is mostly comprised of pollution from human activities.
Delhi has more than 7.4 million vehicles on its roads, with an additional 1,200 added each day leading to the increase in emission of pollutants. 
Stubble burning by farmers in neighbouring states has also been a contributor to the city's misery.

Question 4

Which of the following is/are greenhouse gases?

A.

Nitrogen

B.

Water vapour

C.

Methane

D.

Carbon dioxide

SOLUTION

Solution : B, C, and D

Greenhouse gases are the gases in the atmosphere that are capable of absorbing the infrared radiations from the earth, thereby trapping the heat in the atmosphere. This trapped heat is increasing the global temperature leading to global warming and this phenomenon is known as the greenhouse effect. Examples of greenhouse gases are methane, water vapour, carbon dioxide.

Question 5

It is environmentally important to use unleaded petrol over leaded petrol.

A. True
B. False

SOLUTION

Solution : A

Leaded petrol upon combustion emits more harmful gases into the atmosphere which contains lead as one of their constituents.
It contaminates air, dust, soil, drinking water and food crops. The excessive exposure to lead may cause a permanent loss of intelligence and disruption of behaviour. So, it is important to avoid this and use unleaded petrol.

Question 6

Water pollution can be potentially harmful to aquatic life. What are the ways by which water gets contaminated?

A.

Sewage waste

B.

Chlorination

C.

Industrial waste

D. Boiling 

SOLUTION

Solution : A and C

The main reason for water contamination are the wastes from industries and the sewage. Industrial waste includes any material that is rendered useless during a manufacturing process such as that of factories, industries, mills, and mining operations.Sewage waste includes household waste and waste from local businesses.

Question 7

Identify the popular water purification technique that is used for drinking purposes in domestic cities.

A.

Reverse Osmosis (RO)

B.

Boiling

C.

Chlorination

D.

Melting

SOLUTION

Solution : A

Reverse osmosis often referred to as RO, is an advanced water purification method that was initially developed to produce drinking water from seawater for submarine crews. Modern reverse osmosis units effectively reduce the “dissolved solids” content of water. It is a membrane filtration technology that works by pressing water through the very tiny pores of a semi-permeable membrane to produce a highly purified and great tasting water.

Question 8

While researching on various air pollutants, a scholar Ravi came across gas 'X'. He concluded that 'X' is a poisonous gas and has a strong smell of rotten eggs. Which among the following can be the gas 'X'?

A.

Hydrogen sulfide, H2S

B.

Hydrogen chloride, HCl

C.

Carbon monoxide, CO

D.

Sulphur dioxide, SO2

SOLUTION

Solution : A

Hydrogen sulfide is a chemical compound with the formula H2S. It is a colorless gas with the characteristic foul odour of rotten eggs. It is heavier than air, very poisonous, corrosive, flammable, and explosive.

Question 9

Any unfavorable alteration of the environment may be called as .

A. bioaccumulation
B. environmental pollution
C. biomagnification
D. eutrophication 

SOLUTION

Solution : B

Any unfavorable alteration of the environment may be called as environmental pollution.  

Question 10

Global warming is caused by __________.

A. carbon dioxide
B. chloro fluoro carbons
C. sulphur dioxide
D. nitrogen dioxide

SOLUTION

Solution : A

Global warming is caused by green house gases like carbon dioxide, water vapour, methane etc. Global warming is the steady rise of the Earth's average temperature.