Kerala Syllabus Class 7 Basic Science: Chapter 09 Hurt not the Environment - Questions and Answers


Questions and Answers for Class 7 Basic Science (English Medium) പരിസ്ഥിതിയെ നോവിക്കാതെ | Text Books Solution Basic Science (English Medium) Chapter 09 Hurt not the Environment - Teaching Manual | Teachers Handbook

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ഈ ബ്ലോഗ് അഡ്‌മിൻറ രേഖാമൂലമുള്ള അനുമതിയില്ലാതെ ഈ ബ്ലോഗിൽ നൽകിയിരിക്കുന്ന ചോദ്യോത്തരങ്ങൾ, ഇതേരീതിയിലോ പി.ഡി.എഫ് രൂപത്തിലോ, മറ്റേതെങ്കിലും ഡിജിറ്റലോ, പ്രിന്റഡ് ഉൾപ്പെടെയുള്ള ഏതെങ്കിലും രൂപങ്ങളിലേക്കോ മാറ്റി മറ്റൊരു വെബ്സൈറ്റിലോ, ബ്ലോഗിലോ, യുട്യൂബ്, സോഷ്യൽ മീഡിയാ ഗ്രൂപ്പുകളിലോ ഉൾപ്പെടെ ഒരിടത്തും പ്രചരിപ്പിക്കാൻ പാടില്ലാത്തതാകുന്നു.

Std 7: Basic Science Chapter 09: Hurt not the Environment - Questions and Answers

♦ Observe the picture given below. What sights do you see? 
• Organisms that suffocate due to fumes released while burning solid waste including plastic. 
• Stagnant water bodies due to the dumping of solid waste.

♦ What is the best way to handle waste to reduce air pollution?
Recycling

♦ What is the main toxic gas released when burning plastic waste?
Dioxins  

♦ Have you seen such sights? List such situations you have observed and the problems caused by them.
Situations Problems
• Plastic being burnt• Air gets polluted due to smoke
• Dry leaves are burnt.• Smoke is formed and causes Coughing and shortness of breath
• Burning household waste• Smoke is formed and causes Coughing and shortness of breath
• Garbage is burned on the roads• Ash and smoke are produced
• Waste water from the hotels is released into the rivers• Water pollution, Affects  aquatic plants and animals
♦ Analyse the illustration given below and write your findings.
• Burning waste releases smoke into the air.
• The smoke contains harmful pollutants that cause air pollution.
• Pollutants from burning waste can settle on water bodies, contaminating them.
• Contaminated water affects aquatic life and can be unsafe for humans.
• Unburnt remains and ash can settle on the soil, leading to soil contamination.
• Contaminated soil affects plant growth and reduces soil fertility.
• Pollutants from burning waste cause health issues in humans, animals, and plants.
• The smoke and unburnt remains generated by burning wastes, including plastic, have an adverse impact on air, soil, water and living organisms.

♦ What is the international problem caused by burning waste?
Global warming

♦ Which air pollutant is released the most from burning waste?
Carbon monoxide

♦ What are the health problems of disposing plastic waste in public places?
• Water pollution
• Air pollution
• Soil pollution

♦ Which are the chemical substances released while burning waste materials including plastic? What are the health issues caused as a result of this? 
Chemical substances produced when wastes including plastic are burnt Health issues affecting humans
• Carbon monoxide• Even when a small amount reaches the body problems like headache, fatigue, blurred vision and memory loss occurs. Inhalation of large quantity of carbon monoxide leads to death.
• Sulphur dioxide• Causes cardiovascular and respiratory diseases.
• Nitrogen dioxide• Causes respiratory diseases
• Particulate matter• Inhalation causes itching in throat and eyes, allergy, asthma and lung cancer.
• Dioxins• Increase the risk of cancer, cause thyroid related problems and respiratory diseases.
♦ What are the components present in atmospheric air?
• Nitrogen
• Oxygen
• Carbon dioxide
• Others (Argon, Ozone, Neon, Helium, Krypton, Hydrogen, Xenon, water vapour, dust particles)

♦ Which is the most abundant component?
Nitrogen

♦ What is the quantity of oxygen in air?
21%

♦ Analyse the pie diagram, complete the table and record the quantity of each component. (Textbook Page: 164)
Components of Air Quantity
• Nitrogen• 78%
• Oxygen• 21%
• Carbon monoxide• 0.04%
• Others• 0.96%
♦ Does air pollution cause changes in the components of air?
When the atmospheric air is mixed with chemical substances, the quantity of natural constituents in the air changes

♦ What is Air Pollution?
• Air pollution is caused by the mixing of smoke, toxic gases and other chemical substances in the atmospheric air. 
• Wildfires and natural phenomena like volcanic eruptions and earthquakes also contribute to air pollution. 
• Indiscriminate actions of human beings are the main cause of air pollution.

♦ What are the ways by which air pollution is caused? 
• Burning of waste including plastics 
• Burning of fossil fuels 
• Smoke emitted from vehicles 
• Wildfires
• Mining 
• Burning of agricultural crop residues 
• Use of fireworks 
• Smoke from industries
• Construction activities 
• Volcanic eruption 
• Earthquake
• Use of chemical pesticides

♦ What are the health problems caused by burning waste, including plastic?
• Respiratory problems 
• Heart problems 
• Reproductive problems 
• Skin diseases

♦ What will happen if the amount of oxygen in the air increases or decreases?
• The level of oxygen in the air, both increasing and decreasing, can seriously affect human health and the environment. Normally, the air we breathe should contain approximately 21% oxygen.
• When oxygen levels increase: Increased risk of fire Damage to the lungs and other organs
• When oxygen levels decrease: Can lead to various health problems

♦ Identify the fuel used in each?
Stove Fuel Used
• Firewood stove• Firewood
• Kerosene stove  • Kerosene
• Gas stove• LPG, CNG, Biogas
♦ What chemicals are released when burning fuels such as firewood, kerosene, and cooking gas?
When fuels like wood, kerosene, and cooking gas are burned, the chemical substances released are mainly carbon dioxide, carbon monoxide, nitrogen dioxide, particulate matter, etc. 

♦ What measures should be taken to control air pollution in the kitchen due to the burning of cooking fuels?
• Construction of chimneys 
• Proper ventilation
• Proper stove maintenance

♦ Which are the fuels commonly used in vehicles?
• Petrol
• Diesel
• CNG
• LPG

♦ How does the increase in petrol/diesel vehicles cause air pollution?
When automobile engines are operated using fuels like petrol and diesel, sulphur dioxide, nitrogen dioxide, carbon monoxide and particulate matters are released. Mixing of these with atmospheric air also causes air pollution.

♦ The change in the number of automobiles in Kerala since 2013 is shown in the bar diagram below.
• What was the approximate number of vehicles in 2013?
80 lakhs

• What was the number of vehicles in 2023?
1 core 63 lakhs

• What is the change in the number of vehicles from 2013 to 2023?
The number of vehicles doubled

♦ How can we reduce air pollution by automobiles?
• Use public transport 
• Avoid using large vehicles when travelling alone
• Practice walking and cycling 
• Maintain your vehicle very well
• Switch off the engine when the vehicle needs to be stopped for a long time

♦ How does smoke testing help to reduce air pollution?
• Smoke testing is carried out to find out whether the smoke of vehicles contains more than the permissible amount of harmful chemical substances. 
• By smoke testing, it can be detected whether vehicle emissions contain more harmful chemical substances due to engine failure, age of vehicles and impurities in fuel.

♦ What are the advantages of electric vehicles?
• Electric vehicles do not emit carbon or smoke like petrol/diesel vehicles. 
• Electric vehicles are a solution for air pollution caused by vehicles.
♦ How does air pollution occur? Based on the Pie diagram, prepare a note.
• Air pollution occurs due to various human activities and natural processes that release harmful substances into the atmosphere.

• Dust Particles and Construction Activities (45%): Construction sites generate the largest amount of dust particles into the atmosphere. 

• Burning Waste (17%): The burning of waste materials, including plastics, paper, and organic matter, releases toxic pollutants into the air. 

• Automobiles (14%): When automobile engines are operated using fuels like petrol and diesel, sulphur dioxide, nitrogen dioxide, carbon monoxide and particulate matters are released. Mixing of these with atmospheric air also causes air pollution.

• Diesel Generators (9%): Diesel generators emit pollutants like sulfur dioxide, nitrogen oxides, and particulate matter, which contribute to air pollution.

• Industries (8%): Industrial activities release various pollutants, including sulfur dioxide, nitrogen oxides, and organic compounds. 

• Home Cooking (7%): Burning of fuels like wood, kerosene, and cooking gas causes air pollution.

♦ What are the different forms of water found on the Earth?
• Ice caps, glaciers etc.  
• Water vapour
• Under groundwater
• Oceans
• Lakes
• Rivers

♦ How do water bodies get polluted?
• Disposal of plastic wastes
• Spillage of chemical substances
• Water from sewage.
• Throwing organic wastes into water sources.
• Washing vehicles and bathing cattle in the river.
• Dumping waste from factories.
• Spraying pesticides in agricultural fields
• Dumping waste materials from fish and meat markets.

♦ Given below is the picture of a water body polluted by algae.
♦ What is the reason for this condition of the water body?
Excess growth of water plants like algae in water bodies is caused by a phenomenon known as eutrophication

♦ What is Eutrophication?
The phenomenon of excess growth of water plants like algae in water bodies is known as eutrophication.

♦ What is the reason for Eutrophication?
Eutrophication happens in water bodies where fertilisers containing nitrogen and other similar substances flow in. These excess flowing nutrients cause excessive growth of aquatic plants. 

♦ How does the excess growth of aquatic plants like algae in water bodies affect aquatic ecosystems?
These aquatic plants use oxygen dissolved in water excessively. Due to this, other plants and animals in water die without getting oxygen and the ecosystem that existed in the water body gets disturbed. 

♦ By analysing the pictures given below and observing your surroundings, find out the situations that cause water pollution and write them.
• Excessive use of chemical pesticides
• Discharge of wastewater into drainages
• Dumping of slaughterhouse waste in land and water bodies
• Discharge of waste from industries into water bodies
• Throwing organic wastes into water sources.
• Washing vehicles and bathing cattle in the river.
♦ What are the consequences of water pollution?
• Drinking water gets polluted.
• Causes various waterborne diseases like cholera, typhoid and jaundice.
• The phenomenon of eutrophication occurs.
• Destroys ecosystems
• Chemicals that flow into water affect organisms including humans through plants and aquatic organisms.
• Chemicals that flow into water also pollute the soil.

♦ What measures can we adopt to make water sources free from pollution? 
• Avoid water bodies from pollution.
• Clean every water body by removing pollutants.
• Governments should take necessary action to protect water bodies.
• Avoid dumping waste from fish and meat markets.

♦ Which are the qualities drinking water should have?
• Clearwater 
• Colourless and odourless 
• Free from germs 
• Absence of hazardous chemical substances 
• Presence of adequate mineral salts 
• Neither acidic nor basic

♦ In the following statements, put a tick (✔)mark against the qualities that drinking water should possess.
• Clearwater ✔
• Colourless and odourless ✔
• Free from germs ✔
• Absence of hazardous chemical substances ✔
• Presence of adequate mineral salts ✔
• Salty taste X
• Neither acidic nor basic ✔

♦ What methods do you know to purify drinking water if it is contaminated with impurities? List them out.
• Sifting 
• Boiling
• Sedimentation
• Chlorination
• Distillation

♦ Write the merits and demerits of Some methods to purify drinking water 
• Boiling: Boiling for at least one minute will kill the microorganisms in the water. But the dissolved components in the water will remain.
• Sifting: Undissolved impurities in water are separated by filters. But microbial and dissolved components are not removed.
• Sedimentation: The undissolved impurities are allowed to settle down. The water that appears on top can be separated and used. Microbes and dissolved components cannot be completely removed by this method.
• Chlorination: Adding sufficient quantity of bleaching powder will kill the microorganisms in water. But the components dissolved in the water cannot be removed.
• Distillation: It is the method of boiling water into steam and cooling it to collect pure water. There will be no dissolved components in the water collected in this way.

♦ What are the other ways to purify drinking water? 
• Ultraviolet radiation 
• Reverse osmosis
• Filtration using filters made of nanofibers
• Microfiltration

♦ List out the different kinds of waste formed in a household? 
• Fruit peel
• Vegetable waste 
• Plastic covers
• Footwear
• Plastic bottles
• Used clothes
• Paper
• Toothpaste tube
• Used brushes
• Damaged CFL

♦ What is Biodegradable waste?
Biodegradable wastes are such wastes that decompose and get dissolved in the soil due to the action of microbes. 

♦ What is Non Biodegradable waste?
Microorganisms in soil cannot break down plastic waste, glass pieces, metals, electronic waste, thermocol and the like. Such substances are non-biodegradable wastes.
♦ Classify wastes into biodegradable and non-biodegradable.
Biodegradable Non Biodegradable
• Banana peel
• Food waste
• Paper
• Fish and Meat waste
• Vegetable waste
• Cotton cloth
• Dry leaves
• Plastic covers
• CFL
• Battery
• Footwear
• Toothpaste tube
• Used brushes
• Plastic containers
♦ Which type of waste causes soil pollution?
Nonbiodegradable wastes such as plastic products, pesticides and chemical substances pollute the soil. Metals like Mercury and Cadmium present in CF lamps, computers and electronic products also cause soil pollution. 

♦ Certain household wastes are mentioned below:
Bulbs, food wastes, CF lamps, paper, paper cups, footwear, bags, clothes, pesticide containers, paint containers, plastic bags, vegetable wastes, cardboard packing materials, plastic cups, mobile phone battery, plastic bottles, glass bottles, empty toothpaste tube, fish and meat waste. 
Classify and tabulate them in such a way that they can be deposited in the
appropriate bins shown in the figure. 
Biodegradable Non Biodegradable Hazardous waste
• food wastes
• paper
• paper cups
• vegetable wastes
• cardboard packing materials
• fish and meat waste
• Bulbs
• footwear
• bags
• clothes
• paint containers
• plastic bags
• plastic cups
• plastic bottles
• glass bottles
• empty toothpaste tube
• CF lamps
• pesticide containers
• mobile phone battery
♦ What is meant by Waste Management at source?
• The most appropriate method is to dispose the waste at the source itself. This
is known as waste management at source. 
• Its first step is to segregate the waste at the source itself. 
• Some of the waste sorted out can be used to make organic manure.

♦ Organic manure
Organic waste can be broken down into simpler chemical compounds with the help of microorganisms. They decompose to form nitrate, phosphate and sulphate which are helpful for plant growth. Hence, they can be used as fertilisers.

♦ What are the three main methods of biowaste management at household levels? 
• Vermi composting
• Air contact composting
• Production of biogas

♦ An example of an easy-to-use method for treating green waste is    
Composting

♦ What are the main organisms used in vermicomposting?  
Worm

♦ Vermicompost 
Vermicompost is a fertiliser produced using earthworms. This is also a method of waste management. Plastic containers, large pots and cement tanks are used for vermicomposting. Earthworm takes in organic matter and their excreta turns into manure.

♦ Air Contact Composting
A biocomposter bin is a specially designed-container for waste management. It consists of three containers arranged in tiers. The process taking place in it is air contact composting. This is the best method for waste disposal in houses.

♦ What are the characteristics of the air contact composting process?  
• Less odour.
• Garbage quickly turns to dust.
• The product is of good quality.
• Ensures proper airflow.

♦ What is the main purpose of biowaste treatment?
Build suitable reusable Expressions

♦ Biogas Plant
A biogas plant is a system that converts waste into fuel in the absence of oxygen. In this method, along with waste management, cooking gas is also obtained as a product. 
♦ Paper and paper products can be recycled. But all nonbiodegradable waste cannot be disposed in the same way. Why?
• Hard to dissolve in soil
• Using multiple construction materials in one device
• Life-threatening chemicals
• Increased cost of disposal

♦ Write the merits of biogas plant.
• Biogas plant treats the waste scientifically and protects the environment.
• Biogas plant use helps to reduce pollution in soil, water and air.
• A biogas plant produces biogas using organic waste.
• The organic fertilizer from the biogas plant increases the nutrient quality of the soil.

♦ List the benefits of vermicomposting.
• Improves soil quality.
• Good for plant growth.
• Environmental protection.
• Use of chemical fertilizers can be reduced.
• Soil organic creatures increase.
• Free and low-cost fertilizer.

♦ What would be the reason for banning the production and distribution of very thin plastic covers? 
Plastic products that are very thin cannot be recycled. So, the production and distribution of very thin plastic covers are banned.

♦ What is meant by 3 R’s? 
• Reduce
• Reuse
• Recycle
It is a strategy adopted worldwide to reduce the amount of nonbiodegradable waste.
R- Reduce 
(minimised use)		 R- Reuse (Reusable)
(Only those with
standard grades)		 R- Recycle
(Recyclable)
• Plastic cups• Plastic bags• Metal products
• Plastic, thermocol plates• Plastic jars• Plastic products
• Mineral water bottle• Plastic utensils• Glass products
• Plastic covers
• Plastic bottles
• Paper
♦ Haritha Karma Sena
In our state, Haritha Karma Sena is playing a major role in transporting nonbiodegradable waste to the treatment centers.
Activities of Harita Karma Sena
• Haritha Karma Sena members collect non-biodegradable waste from households and establishments. 
• Haritha Karma Sena members separate waste into recyclable, and non-recyclable. 
• Deliver the raw material once a month to the houses and institutions adopting the composting method.
• Haritha Karma Sena members educate the public about waste segregation, recycling, and the harmful effects of waste dumping and burning. 

♦ What are the benefits of bio-compost?
Improves soil structure  

♦ What are the microorganisms used in making bio-compost?  
Bacteria, Fungus  

♦ Which wastes are mainly used in making bio-compost?  
Vegetable waste  
Let’s Assess

1. Observe the diagrams given below. Find out how the air is gets polluted in each situation and complete the table.
Situation Ways of air pollution Consequences
• Construction Work• release dust particles
into the air		• Respiratory Issues
• Demolition of buildings• large amount of dust
and debris		• Respiratory Issues
• Working of diesel engine• emitting smoke• health issues
• global warming
• Factory Chimney• emitting smoke• acid rain
• Increased number of vehicles• emissions of harmful gases• Climate Change
• global warming
3.  Identify the correct statements regarding plastic waste management from those given below: 
a) Thin plastic products should be burnt.
b) Plastic products should be recycled as much as possible.
c) Plastic products should be reused as much as possible.
d) Use of plastic products should be minimised. 
Correct statements:
b) Plastic products should be recycled as much as possible.
c) Plastic products should be reused as much as possible.
d) Use of plastic products should be minimised. 

4.  Which method of purification can be adopted to separate freshwater from seawater?
a) Sifting
b) Chlorination
c) Distillation
d) Sedimentation 
Answer: c) Distillation




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