STD-5, CHAPTER- 9:FUELS, EXTRA QUESTION ANSWERS

1.      What is a fuel?

Ans: A substance that produces energy on burning is called a fuel.

2.      State the main function of a fuel.

Ans: The main function of a fuel is to produce energy on burning.

3.      Name the types of fuel.

Ans: Fuels are available in solid, liquid or gaseous forms.

4.      Give some examples of solid fuels.

Ans: Wood, coal, coke and cowdung are some examples of solid fuels.

5.      Give some examples of liquid fuels.

Ans: Kerosene, petrol and diesel are some examples of liquid fuels.

6.      Name some gaseous fuels.

Ans: LPG, CNG, PNG and biogas are examples of gaseous fuels.

7.      LPG stands for _______.

Ans: Liquefied petroleum Gas

8.      CNG stands for _______.

Ans: Compressed Natural Gas

9.      PNG stands for ______.

Ans: Piped Natural Gas

10.  Why do we need energy?

Ans: We need energy for cooking, for movement of trains, automobiles and aeroplanes, for generating electricity, for running various machines and so on.

11.  Name some domestic fuels.

Ans: Wood, cowdung cakes, coal, kerosene, LPG, PNG and biogas are some domestic fuels.

12.   Why is biogas regarded as a better fuel than cowdung cakes?

Ans: i) Cowdung cakes produce smoke whose concentration can be as much as five times higher than that produced by ordinary coal.

ii) Biogas, on the other hand, does not produce smoke and are more efficient. They are eco-friendly. Thus, they are regarded as a better fuel than cowdung cakes.

13.  How can we use the ash, obtained by burning coal?

Ans: The ash, a by-product of coal combustion, is used as a filler for things like the tennis rackets and golf balls.

14.  Name some cleaner fuels. Why are they named so?

Ans: i) LPG, CNG, PNG and biogas are cleaner fuels.

ii) They are named so, because they do not produce smoke on burning and do not leave any ash after burning.

15.  How the modern trains different from earlier trains?

Ans:i) Earlier, trains were run with the help of steam engines. In these engines, steam was produced by burning coal.

ii) Now-a-days, train engines use either electricity or diesel.

16.  Vehicles, like buses, cars and scooters run on ______.

Ans: Petrol or diesel

17.  Aeroplanes commonly use a highly refined kerosene based fuel known as _____.

Ans: Aviation Turbine Fuel (ATF).

18.  Why is CNG called a better green fuel?

Ans:i) CNG do not produce smoke on burning and do not leave any ash after burning.

ii) CNG powered vehicles have lower maintenance costs and better efficiency.

iii) It causes less air pollution, is more eco-friendly and causes less harm to the health of humans and animals.

Therefore, CNG is called a better green fuel.

19.  How is coal used by powerhouses for generating electricity?

Ans:i) Powerhouses often burn coal to convert water into steam.

ii) This steam energy is used to operate turbines which in turn, help to generate electricity.

20.  What are the modern methods of producing electricity/

Ans: Electricity is now being produced by using the energy stored in water and also by using wind energy and energy of the sun.

21.  Petrol, diesel and kerosene are all obtained by refining _______.

Ans: Crude oil (petroleum)

22.   What are fossil fuels?

Ans: Fuels which are formed from decomposition of living things over a period of millions of years.

23.  Name the three main fossil fuels.

Ans: Coal, crude oil (petroleum) and natural gases are the three main fossil fuels.

24.  How have fossil fuels been formed?

Ans: i) Fossil fuels are formed by decomposition of animal and plant matter, buried deep under the surface of earth, at high temperature and pressure prevailing there.

ii) Over a period of millions of years, these animal and plant matter got changed into fossil fuels.

25.  Describe the three main fossil fuels.

Ans: The three main natural fossil fuels are, coal, crude oil (petroleum) and natural gas.

i) Coal- It is a combustible black sedimentary rock. It is primarily used for production of heat and electricity.

ii) Crude oil (petroleum) – This was formed from dead sea-creatures. These dead sea-creatures fell to the sea-bed where their bodies underwent chemical changes due to bacteria.

iii) Natural Gas- This was formed in the same way as crude oil. It is often collected when drilling for oil.

26.  When is a source of energy said to be a renewable source of energy? Give some examples of such sources.

Ans: The sources of energy which is freely available and which can be readily replenished, are said to be a renewable source of energy. Examples of renewable sources of energy are, Solar energy, tidal energy, wind and biomass.

27.  Define biomass.

Ans: The waste matter of animals and plants are called biomass.

28.  When a source of energy said to be a non-renewable source of energy? Give two examples of such sources.

Ans: Sources of energy, which once used, cannot be readily replenished are called non-renewable sources of energy.

ii) Coal and petroleum are two of the non-renewable sources of energy.

29.  Define Hydroelectricity.

Ans: Electricity, generated by using the energy of water, is called hydroelectricity.

30.  State two disadvantages of fossil fuels.

Ans: i) Fossil fuels are non-renewable sources of energy.

ii) They are also a major cause of environmental pollution.

31.  Why should efforts need to be made to reduce the use of fossil fuels?

Ans: i) Fossil fuels are available in limited quantity and are not likely to last for a long time.

ii) They are also a major cause of environmental pollution.

We should, therefore, make efforts to reduce the use of fossil fuels.

STD-3, CHAPTER-5: ANIMALS, EXERCISE QUESTION ANSWERS

 A.     FILL IN THE BLANKS.

1.      Land animals generally walk on ______ legs.

Ans: four

2.      Desert animals can tolerate _______ temperatures.

Ans: high

3.      Penguin is found in _______ covered regions.

Ans: snow

4.      Piranha is found in _____ water of lakes and rivers.

Ans: fresh

5.      Orangutan does not like to interact with _______.

Ans: humans

6.      Terrestrial animals live on ______.

Ans: land

B.      MATCH THE FOLLOWING:

1.      dog                                  a. crawls on the ground

2.      camel                              b. people often keep it as a pet.

3.      snake                              c. can live without water for many days

4.      toad                                d. has thick fur on its body

5.      polar bear                      e. lives both on land and in water

      Ans:

1.      dog                               b. people often keep it as a pet

2.      camel                           c. can live without water for many days

3.      snake                           a. crawls on the ground

4.      toad                             e. lives both on land and in water

5.      polar bear                  d. has thick fur on its body

 

C.      TICK THE CORRECT OPTION.

 

1.      This animal lives in a desert -

(a)   tiger        (b) lion          (c) camel        (d) dog

      Ans: camel

2.      An animal, that lives in very cold regions, is the –

(a)   penguin          (b)  snake       (c) zebra          (d) parrot

      Ans: penguin

3.      An animal, that lives in a burrow, is a –

(a)   fish       (b)  giraffe       (c) penguin       (d) snake

       Ans: snake

4.      Nature protects polar bears from cold, by providing them with –

(a)   Webbed feet       (b)  beak       (c) fur       (d) gills

       Ans: fur

5.      It is not an aquatic animal–

(a)   fish          (b) turtle        (c) rabbit          (d) starfish

      Ans: rabbit

D.     ANSWER THE FOLLOWING QUESTIONS IN BRIEF.

 

1.      Name any four land animals.

Ans: Horse, cow, dog, cat, are four land animals.

2.      Name any two things that forests provide to animals.

Ans: Forests provide food and shelter to animals.

3.      How do fins and gills help a fish?

Ans: Fins help a fish to swim and gills help it to breathe.

4.      Why do frogs need water?

Ans: Frogs need water for laying their eggs.

5.      Why dogs and cats are favourite pets of many people?

Ans: i) Dogs and cats like to interact and play with humans.

ii) They can learn the tricks and can play games.

iii) They also love their masters.

So, dogs and cats are favourite pets of many people.

E.      ANSWER THE FOLLOWING QUESTIONS.

 

1.      State the special features which help a camel to live in a desert.

Ans: i) Camels can tolerate high temperatures.

ii) Camels can store water and food in their bodies.

iii) Camels have padded feet that help them to walk on sand.

2.      How do skin colours and body patterns of some animals help to save them from danger?

Ans: i) The colour of the skin and body patterns of some animals, help them to merge with their surroundings so that their enemies cannot see them.

ii) Thus the skin colours and body patterns of some animals help to save them from danger.

3.      Why are dolphins considered to be intelligent animals?

Ans: i) Dolphins can easily learn to perform tricks and play games.

ii) So, dolphins are considered to be intelligent animals.

STD-3, CHAPTER-6: FEEDING HABITS OF ANIMALS, EXERCISE QUESTION ANSWERS

 A.     FILL IN THE BLANKS.

1.      Snakes ________ their prey.

Ans: Swallow

2.      Giraffe feeds on ­­­_______ only.

Ans: plants

3.      Frog has a _______ tongue.

Ans: sticky

4.      Buffaloes ________ their food first and then chew it.

Ans: nibble

5.      Butterfly _______ its food.

Ans: sucks

6.      Squirrel has sharp front _______ like teeth.

Ans: chisel

B.      MATCH THE FOLLOWING:

1.      snake                                  a. sugarcane

2.      monkey                              b. frog

3.      lion                                     c. banana

4.      elephant                            d. deer

      Ans:

1.      snake                               b. frog

2.      monkey                           c. banana

3.      lion                                  d. Deer

4.      elephant                         a. sugarcane

 

C.      TICK THE CORRECT OPTION.

 

1.      The animal, that eats both plants and animals, is the -

(a)   tiger        (b) cow          (c) rat        (d) horse

      Ans: rat

2.      Dog tears the flesh with –

(a)   Chisel teeth          (b) grinding teeth         (c) pointed teeth          (d) tube

      Ans: pointed teeth

3.      Poultry birds should be fed with–

(a)   Green grass       (b)  fresh fruits       (c) milk       (d) grains

       Ans: grains

4.      It is a herbivorous animal–

(b)   fox          (b) cow        (c) rat          (d) snake

      Ans: cow

D.     ANSWER THE FOLLOWING QUESTIONS IN BRIEF.

 

1.      What are carnivorous animals?

Ans: Flesh eating animals are called carnivorous animals.

2.      Name the kind of teeth that help a cow to chew the grass.

Ans: Strong and broad back teeth, help a cow to chew the grass.

3.      Name two animals which gnaw their food.

Ans: Two animals which gnaw their food are, rabbit and rat.

4.      Name the type of teeth that squirrels have. Name two more animals having the same type of teeth.

Ans: Squirrels have sharp pointed chisel like teeth. Two more animals having the same type of teeth are, rabbit and rat.

E.      ANSWER THE FOLLOWING QUESTIONS.

 

1.      State one difference between herbivorous and omnivorous animals. Give one example of each type.

Ans: i) Herbivorous animals only eat plant products. Omnivorous animals eat both plant and animal products.

ii) Cow is a herbivorous animal and dog is an omnivorous animal.

2.      How does a lizard take its food?

Ans: i) A lizard catches its prey with the help of its sticky tongue.

ii) Lizards swallow their food without biting ir chewing the food.

3.      Explain the term ‘chewing the cud’?

Ans: i) Grass eating animals first nibble their food and put it inside their bodies.

ii) When they relax, they bring back part of the food into their mouths and then chew it properly. This is called ‘chewing the cud’.

4.      Write any two ways that can help us in taking care of domestic animals.

Ans: Two ways that can help us in taking care of domestic animals are as follows,

i) Poultry birds, like hen and duck, should be fed with grains and water.

ii) The shelter of all domestic animals should be clean, dry, and airy.

5.      How do butterfly and mosquito have their food?

Ans: Butterfly and mosquitoes, have a long hollow tube like structure. This helps them to suck their food.

STD-4: CHAPTER-7: FOOD, EXERCISE QUESTION ANSWERS

 A.     FILL IN THE BLANKS.

1.      Carbohydrates and fats are the nutrients which provide _______ to our body.

Ans: energy

2.      Foodstuffs, containing _______, are called body building foods.

Ans: proteins

3.      _______ and _______ are the sources of Vitamin C.

Ans: Orange and lemon

4.      We can get ________ from iodised table salt.

Ans: iodine

5.      The roughage in our diet, helps the body to get rid of_______ food.

Ans: undigested

B.      WRITE TRUE OR FALSE FOR THE FOLLOWING STATEMENTS:

1.      All nutrients are important for our body.                                                                            True

2.      Our food should include more than one source of protein.                                            True

3.      Our body needs Vitamin C for healthy bones and teeth.                                                 False

4.      A balanced diet need not contain all the nutrients.                                                          False

5.      Old People, who are not very active, should eat more of fats and carbohydrates.   False

 

C.      TICK THE CORRECT OPTION.

 

1.      Calcium, Iron and Phosphorus are examples of-

(a)   Minerals        (b) Vitamins          (c)  Proteins       (d) Carbohydrates

      Ans: Minerals

2.      Protective foods are needed by our body for –

(a)   energy       (b) warmth           (c) health           (d) growth

      Ans: health

3.      A person, doing a lot of physical work, needs more of –

(a)   vitamins       (b)  minerals       (c) proteins       (d) carbohydrates

       Ans: carbohydrates

4.      Sugar contains mainly–

(a)   Carbohydrates       (b)  vitamins       (c) minerals       (d) fats

       Ans: carbohydrates

5.      The vitamin, that helps us to have good eye-sight, is Vitamin–

(a)   A       (b) B           (c) C           (d) D

      Ans: Vitamin A

D.     ANSWER THE FOLLOWING QUESTIONS IN BRIEF.

1.      Name the nutrients present in energy giving foods.

Ans: Energy giving foods contain fats and carbohydrates in them.

2.      State the main role of proteins for our body.

Ans: Proteins help our body to grow and repair the worn-out tissues.

3.      Name two food items, obtained from animals, that are good sources of proteins.

Ans: Milk and eggs, that are obtained from animals, are good sources of proteins.

4.      Name two minerals that are required for healthy bones and teeth. Also mention one food source that contains both of them.

Ans: Calcium and Phosphorus are required for healthy bones and teeth. Milk contains both calcium and phosphorus.

5.      Why are vitamins and minerals called ‘protective foods’?

Ans: Vitamins and minerals, protect our body from diseases and keep us healthy. So, foodstuffs containing vitamins and minerals are called protective foods.

E.      ANSWER THE FOLLOWING QUESTIONS.

1.      What are nutrients? Why are they necessary for our body?

Ans: i) Nutrients are substances, present in the food.

ii) They provide us energy, help us to grow, keep us healthy, disease free and strong. So, nutrients are necessary for our body.

2.      Why should we eat a balanced diet?

Ans: i) All nutrients are not available in any one food item.

ii) Absence of any one nutrient from our diet, over the years, can affect our growth and proper functioning of the body.

iii) A balanced diet contains all the nutrients, roughage and water in appropriate amounts.

So, we should eat a balanced diet.

3.      Why is it advisable to eat food items like whole fruits, salads and whole grains?

Ans: : i) Whole fruits, salads and whole grains contain fibres or roughage.

ii) These fibres helps our body to get rid of undigested food.

iii) Fibres also help us to avoid over-eating.

So, it is advisable to eat food items like whole fruits, salads and whole grains to get fibres.

4.      Why do we say that water is essential for proper functioning of our body?

Ans: i) Water helps in digestion of food and absorption of nutrients in our body.

ii) It also helps in throwing out wastes from the body.

Thus, water is essential for our body to function properly.

5.      ‘Old people need less of proteins, carbohydrates and fats than young children.’ Justify this statement.

Ans: i) Young children are very active, as they do a lot of work. They require more energy and strength. So, they need more proteins, carbohydrates and fats.

ii) But, old people are not very active. They need less energy. So, they need less carbohydrates, fats and proteins.