STD-5: CHAPTER-8- PROPERTIES OF WATER, EXERCISE QUESTION AND ANSWERS

 A.     FILL IN THE BLANKS.

1.      A substance which dissolves completely in a liquid is said to be ________ in it.

Ans: soluble

2.      The substance, that dissolves in a medium to form a solution, is known as the ______.

Ans: solute

3.       Mustard oil is _________ in water.

Ans: insoluble

4.       Aquatic animals breathe the _______ gas dissolved in water.

Ans: oxygen

5.      Change of a liquid into its vapour form is called ________.

Ans: evaporation

6.      Condensation is the process of change of vapours into _______.

Ans: liquid

B.      WRITE TRUE OR FALSE FOR THE FOLLOWING STATEMENTS.

 

1.      Sugar and salt are soluble in water.                                                                                True

2.      Hair oil is insoluble in water.                                                                                            True

3.      Pebbles float on water.                                                                                                      False

4.      Sand sinks in water.                                                                                                            True

5.      Water vapours can be changed into liquid water by heating.                                   False

 

C.      TICK THE CORRECT OPTION.

 

1.      In a solution of sugar and water -

(a)   Water is the solute                

(b)   Sugar is the solvent        

(c)    Both water and sugar are solutes           

(d)   Water is the solvent

      Ans: Water is the solvent

2.      When sand is mixed with water, it-

(a)   Dissolves and floats on water        

(b)   Does not dissolve but floats on water          

(c)    Does not dissolve but sinks in water         

(d)   Dissolves and sinks in water

      Ans: does not dissolve but sinks in water

3.      Wet clothes get dried due to-

(a)   Water cycle       (b) evaporation        (c) respiration       (d) condensation

       Ans: evaporation

4.      Mixture of sugar, salt and lemon juice in water is a-

(a)   solution                (b) solvent

(c)    solute                    (d) floating mixture

      Ans: solution

D.     ANSWER THE FOLLOWING QUESTIONS IN BRIEF.

 

1.      Define a solution.

Ans: When a substance (solute) dissolves completely in any medium (solvent), we get a solution.

2.      What is a solvent?

Ans: The medium, in which the substance (solute) is dissolved, is called a solvent.

3.      Name two substances that are soluble in water.

Ans: Sugar and salt are soluble in water

4.      Name two substances that are insoluble in water.

Ans: Pebbles, saw dust are insoluble in water.

5.      Write the names of four substances that float on water.

Ans: Cork, Butter paper, hair oil, mustard oil float on water.

6.      Name the three forms of water.

Ans: The three forms of water are liquid, solid and vapour form.

E.      ANSWER THE FOLLOWING QUESTIONS.

 

1.      Give two examples each of:

(a)   Liquids which dissolve in water

(b)   Liquids which are insoluble in water.

(c)    Solids which float on water.

(d)   Solids which sink in water

Ans: a) lemon juice and vinegar are the liquids which dissolve in water.

b) hair oil, kerosene are the liquids which are insoluble in water.

c) cork and saw dust are the solids which float on water.

d) pebbles and coins are the solids which sink in water.

2.      What do we understand by the terms ‘evaporation’ and ‘condensation’?

Ans: i) Change of a liquid into its vapour form is called Evaporation.

ii) Change of vapour form of a substance into its liquid form, on cooling, is called condensation.

3.      How are clouds formed?

Ans: i) Due to evaporation, the water from different water bodies, rises up in the form of water vapour.

ii) As these go very high, they get cooled and condense to form tiny droplets of liquid water.

In this way, clouds are formed.

4.      How does rain water get impure?

Ans: i) Raindrops, when just formed, are the purest form of water.

ii) By the time, rain water reach the surface of the earth, they dissolve many harmful gases present in air and also get dust and smoke mixed up with them.

Thus, it becomes impure.

STD 5: CHAPTER 7: IMPORTANCE OF WATER, EXERCISE QUESTION AND ANSWERS

 

A.     FILL IN THE BLANKS.

1.      Water helps in _______ of food in animals.

Ans: digestion

2.      Animals living in water are called _________.

Ans: aquatic animals

3.       Animals which can live both in water and on land, are called _________.

Ans: amphibious animals

4.       Water, trapped between underground rocks, is called ________.

Ans: ground water

5.      ______ and ______ are aquatic plants.

Ans: duckweed and lotus

B.      WRITE TRUE OR FALSE FOR THE FOLLOWING STATEMENTS.

 

1.      Water is required for germination of seeds.                                                                 True

2.      Ground water can be drawn up by a hand pump.                                                       True

3.      About 50% of water is present in seas and oceans.                                                    False

4.      Octopus is an amphibious animal.                                                                                  False

5.      River water is purified for drinking purpose.                                                                True

 

C.      TICK THE CORRECT OPTION.

 

1.      About 97% of water is present in -

(a)   Seas and oceans                (b) lakes         (c) ponds           (d) glaciers

      Ans: seas and oceans

2.      Plants absorb water from the soil with the help of -

(a)   stem         (b) leaves         (c) branches         (d) roots

      Ans: roots

3.      A rehat is used for-

(a)   Supplying water through taps.

(b)   Purifying river water          

(c)    Drawing out ground water for irrigation      

(d)   Absorbing water from the soil

       Ans: drawing out ground water for irrigation

4.      An example of an amphibious animal is-

(a)   fish                           (b) frog

(c)    hydrilla                    (d) duckweed

      Ans: frog

D.     ANSWER THE FOLLOWING QUESTIONS IN BRIEF.

 

1.      Name any two water bodies that exist on the surface of earth.

Ans: Seas and oceans are the water bodies that exist on the surface of earth.

2.      What are animals living in water known as? Write names of two such animals.

Ans: The animals living in water are known as aquatic animals. Examples are, fish and octopus.

3.      What are amphibious animals?

Ans: Animals, which can live both in water and on land, are called as amphibious animals.

4.      Write names of four aquatic plants.

Ans: Four aquatic plants are, water lily, duckweed, lotus and water hyacinth.

5.      How do plants absorb water from the soil?

Ans: The plants absorb water from the soil with the help of their roots.

6.      State two common methods of drawing out ground water.

Ans: Two common methods of drawing out ground water are using a rehat or a pulley.

E.      ANSWER THE FOLLOWING QUESTIONS.

 

1.      Besides its domestic use, state three other uses of water.

Ans: Besides its domestic use, water is also used for, i) irrigating the fields,

                                                                                                 ii) generating electricity and  

                                                                                                 iii) transportation

2.      How does water help in excretion of waste material from animal bodies?

Ans: i) The animal body produces waste materials.

ii) These waste materials get dissolved in water and are excreted in the form of urine or sweat.

3.      List any four ways in which water is important for plants.

Ans: i) Water provides nutrients to plants in dissolved form.

ii) Water also helps in transporting nutrients to various parts of the plant.

iii) Plants require water for photosynthesis process.

iv) Plants require water for germination of seeds.

4.      How can ground water be drawn out through tubewells?

Ans: i) In a tubewell, a long pipe is inserted deep into the ground where it dips below the ground water level.

ii) Water is then drawn up by using a hand pump or an electric pump.

5.      What is a stepwell?

Ans: i) A stepwell is a well having steps on all sides.

ii) This enables people to go down to fetch water.

6.      How is water supplied in cities?

Ans: i) There are well-planned water supply systems that supply water to homes and offices in the cities.

ii) In such systems, the river water is usually purified by a series of processes that make it fir for drinking.

iii) This purified water is then sent to homes and offices through a network of pumps and pipes.

 

STD-5, CHAPTER-6: SPOILAGE AND WASTAGE OF FOOD AND FOOD PRESERVATION, EXERCISE QUESTION AND ANSWERS

 

A.     FILL IN THE BLANKS.

1.      Micro-organisms like bacteria and ________ spoil the food.

Ans: Fungi

2.      Insects make their home in _______ and _______ places.

Ans: moist and dark places

3.       Enzymes can be harmful because they can cause ______ of fruits and vegetables.

Ans: spoilage

4.       Snacks, like biscuits and chips, should be stored in _______ jars.

Ans: airtight

5.      The growth of micro-organisms slows down at _______ temperatures.

Ans: lower

B.      WRITE TRUE OR FALSE FOR THE FOLLOWING STATEMENTS.

 

1.      Growth of bread moulds, on bread, indicates that it has got spoiled.                    True

2.      Vinegar is used as a preservative.                                                                                   True

3.      It is safe to drink unpastuerised milk.                                                                            False

4.      We can eat more than the required quantity.                                                              False

5.      We may eat spoiled food rather than wasting it.                                                         False

 

C.      TICK THE CORRECT OPTION.

 

1.      A natural insect repellent, found in our kitchens, is -

(a)   salt                (b) sugar         (c) turmeric powder           (d) wheat flour

      Ans: turmeric powder

2.      Dry foods, like cereals and nuts, are preserved by -

(a)   Adding salt and sugar         (b) vacuum packing          (c) dehydration         (d) pasteurisation

      Ans: vacuum packing

3.      Fruits and vegetables get ripened due to the action of-

(a)   enzymes       (b) bacteria        (c) fungi       (d) insects

       Ans: enzymes

4.      The least perishable food item, from the following, is-

(a)   milk                      (b) biscuits

(c)    meat                    (d) curd

      Ans: curd

5.      The chances of spoilage of food can be reduced by keeping the food -  

(a)   moist       (b) warm        (c) at low temperatures       (d) in open containers

       Ans: at low temperatures

D.     ANSWER THE FOLLOWING QUESTIONS IN BRIEF.

 

1.      State two factors that contribute to the fast growth of micro-organisms.

Ans: Two factors that contribute to the fast growth of micro-organisms are, moisture and temperature.

2.      What is likely to happen to curd if it is not stored in the refrigerator?

Ans: If curd is not stored in the refrigerator, then it is likely to change its smell and will become sour. In other words, it will get spoiled.

3.      What do you understand by food preservation?

Ans: Food preservation is the process of treating and handling of food to stop, or slow down, the spoilage caused by micro-organisms.

4.      How can we protect our food from insects, worms and rats?

Ans: i) We should keep the cupboards, shelves and containers clean and dry.

ii) This will prevent them from making a home at places where our food items are kept.

5.      Why does food stay fresh for a longer time when stored in a refrigerator?

Ans: i) The temperature is low inside a refrigerator.

ii) Micro-organisms and enzymes get deactivated at low temperatures and hence, the spoilage of food gets prevented.

E.      ANSWER THE FOLLOWING QUESTIONS.

 

1.      Give any three reasons for spoilage of food.

Ans: Three reasons for spoilage of food are, micro-organisms, enzymes, insects, worms and rats.

2.      How is food preservation useful to us?

Ans: Food preservation is helpful in many ways:

i)                    It helps to maintain nutritive value of food.

ii)                  It increases the shelf life of food, thus, increasing its supply. Many perishable foods can be preserved for a long time.

iii)                It makes seasonal foods available throughout the year.

3.      Why is it important to check the manufacturing and the expiry date of packaged food items before consuming them?

Ans: Some food items are preserved by the process of canning, bottling or by vacuum packing. But, these food items start to spoil after a certain period of time. So, it is important to check the manufacturing and the expiry date of packaged food items before consuming them.

4.      Explain the following methods of food preservation:

(a)   Dehydration  (b) Canning and Bottling    (c) Pasteurisation

Ans: a) Dehydration: The process of food preservation in which water content of the food stuff is removed, is called dehydration.

b) Canning and Bottling: Food is cooked and sealed in sterile cans or jars and these containers are boiled to kill any remaining bacteria.

c) Pasteurisation: In this process, food product is subjected to pressurised heating, for a short time, followed by immediate cooling.

5.      Rakesh bought two raw papayas. He kept one papaya in the refrigerator and other papaya on the kitchen shell. Which will ripen and Why?

Ans: The papaya kept in the kitchen shell will ripen faster, due to the action of enzymes. Whereas, the action of enzymes slows down for the papaya, which is kept at a low temperature inside the refrigerator.

STD-4, CHAPTER-6: INSECTS, EXERCISE QUESTION AND ANSWERS

 A.     FILL IN THE BLANKS.

1.      Butterflies are attracted to ______ flowers

Ans: coloured or scented (both are correct)

2.      Honeybees suck ______ from flowers.

Ans: nectar

3.      The six-sided chambers of beehives are called ________.

Ans: Combs

4.      Malaria is spread by the bite of female _________.

Ans: Anopheles

5.      The cover, weaved by a silk moth, around itself is called a _______.

Ans: Cocoon

6.      Bees and ______ are stinging insects.

Ans: wasp

B.      WRITE TRUE OR FALSE FOR THE FOLLOWING STATEMENTS:

1.      Insects help in pollination.                                                               True

2.      Lac insects grow on banyan trees.                                                 True

3.      Houseflies spread malaria.                                                              False

4.      Aedes mosquito spreads dengue.                                                  True

5.      Bubonic plague is caused by a mosquito.                                     False

 

C.      TICK THE CORRECT OPTION.

 

1.      The insect, that usually spreads jaundice, is the-

(a)   Mosquito        (b) wasp          (c)  housefly       (d) butterfly

      Ans: housefly

2.      Honeybees make honey from –

(a)   lac       (b) nectar           (c) milk           (d) sugar

      Ans: nectar

3.      The sting of insects, like the bees and wasps, is located on their –

(a)   wing       (b)  back       (c) mouth       (d) leg

       Ans: back

4.      An insect, that helps to save our crops from pests, is the–

(b)   wasp       (b)  lady bird beetle       (c) bee       (d) butterfly

       Ans: lady bird beetle