SaraNextGen.Com
Updated By SaraNextGen
On March 11, 2024, 11:35 AM

INTRODUCTION - Chapter 18 Pollution Of Air & Water class 8 ncert solutions Science - SaraNextGen [2024]


Question 1:

What are the different ways in which water gets contaminated?

Answer:

Water gets contaminated by the addition of:

(i) Agricultural chemicals: Farmers use excessive amounts of pesticides and fertilizers to increase crop production. These chemicals get carried away to the water bodies due to rains and floods which lead to water pollution.

(ii) Industrial wastes: Industries release harmful chemical wastes into water sources, thereby polluting them.

(iii) Sewage wastes: Waste materials from kitchens, toilets, and laundry sources are also responsible for contaminating water.

Question 2:

At an individual level, how can you help reduce air pollution?

Answer:

An individual can reduce air pollution by:

(i) Avoiding the use of cars as much as possible and by using public transport whenever possible.

(ii) By not using vehicles for short distances.

(iii) By using clean fuels such as LPG and CNG instead of diesel and petrol.

(iv) Always disposing the garbage properly and not burning it.

(v) Controlling the emissions from vehicles and household chimneys.

Question 3:

Clear, transparent water is always fit for drinking. Comment.

Answer:

No. Clear and transparent water is not always fit for drinking. Water might appear clean, but it may contain some disease causing micro-organisms and other dissolved impurities. Hence, it is advised to purify water before drinking. Purification can be done by water purifying systems or by boiling the water.

Question 4:

You are a member of the municipal body of your town.

Make a list of measures that would help your town to ensure the supply of clean water to all its residents.

Answer:

To ensure the supply of clean water to all residents the following steps must be taken:

(i) The main water source must be built in clean surroundings and should be maintained properly.

(ii) Chemical methods such as chlorination must be used for purifying water.

(iii) The area around water pipes must also be clean.

Question 5:

Explain the differences between pure air and polluted air.

Answer:

Pure air contains around 78% nitrogen, 21% oxygen, and 0.03% carbon dioxide. Other gases such as argon, methane, ozone, and water vapours are also present in small quantities. When this composition of air is altered by the addition of harmful substances or gases such as nitrogen dioxide, sulphur dioxide, carbon monoxide, and particulate matter, then the air is said to be polluted.

Question 6:

Explain circumstances leading to acid rain. How does acid rain affect us?

Answer:

Burning of fossil fuels such as coal and diesel releases a variety of pollutants such as sulphur dioxide and nitrogen dioxide into the atmosphere. These pollutants react with water vapours present in the atmosphere to form sulphuric acid and nitric acid respectively. These acids come down with the rain, thereby resulting in acid rain.

Effects of acid rain:

(i) Acid rains damage crops.

(ii) Acid rains corrode buildings and structures especially those made of marble such as Taj Mahal.

Question 7:

Which of the following is not a greenhouse gas?

(a) Carbon dioxide

(b) Sulphur dioxide

(c) Methane

(d) Nitrogen

Answer:

(d) Nitrogen

Also Read : Page-No-253:-Chapter-18-Pollution-Of-Air-&-Water-class-8-ncert-solutions-Science

SaraNextGen