NCERT Solutions for Class 6 Science Chapter 15 Air Around Us

Chapter 15
Air Around Us

1. What is the composition of air?
Ans- Air is a mixture of nitrogen, oxygen, carbon dioxide, water vapour and few gases. Some dust particles may also present in it.

2. Which gas in the atmosphere is essential for respiration?
Ans- Oxygen gas in the atmosphere is essential for respiration.

3. How will you show that air supports burning?
Ans- Take a small burning candle. Cover the burning candle with a glass jar. After few minutes the candle is extinguished. As the supply of air stopped due to glass jar the burning candle is also stopped. This experiment proves that air supports burning.

4. How will you show that air is dissolved in water?
Ans- Take a glass filled with water. On heating, bubbles are seen in the water. The bubbles are formed before water reaching its boiling point indicates dissolve air in water.

5. Why does a lump of cotton wool shrink in water?
Ans- Lump of cotton wool has air among gaps of cotton fibres. When water replaces the air from these gaps, the cotton lump becomes heavy and also shrinks due to removal of air gaps.

6. The layer of air around the earth is known as Atmosphere

7.The component of air used by green plants to make their food, is Carbon dioxide

8. List five activities that are possible due to presence of air.
Ans- Activities that are possible due to the presence of air are:
a) Winnowing
b) Photosynthesis
c) Respiration
d) Transpiration
e) Formation of cloud.

9. How do plants and animals help each other in exchange of gases in the atmosphere?
Ans- Animals and plants use oxygen from air during respiration and release carbon dioxide gas in air. But green plants also release oxygen gas by using carbon dioxide during photosynthesis. Thus, we can say that animals and plants help each other in exchange of gases.

NCERT Solutions for Class 6 Science Chapter 14 Water

Chapter 14
Water

 
1. Fill up the blanks in the following:

(a) The process of changing of water into its vapour is called evaporation or vaporisation.
(b) The process of changing water vapour into water is called condensation.
(c) No rainfall for a year or more may lead to droughts in that region.
(d) Excessive rains may cause flood .


2. State for each of the following whether it is due to evaporation or condensation:

(a) Water drops appear on the outer surface of a glass containing cold water.  Condensation
(b) Steam rising from wet clothes while they are ironed. Evaporation
(c) Fog appearing on a cold winter morning.
Condensation

(d) Blackboard dries up after wiping it.
Evaporation

(e) Steam rising from a hot girdle when water is sprinkled on it.
Evaporation

3. Which of the following statements are “true”?

(a) Water vapour is present in air only during the monsoon. False
(b) Water evaporates into air from oceans, rivers and lakes but not from the soil. False
(c) The process of water changing into its vapour is called evaporation. True
(d) The evaporation of water takes place only in sunlight. False
(e) Water vapour condenses to form tiny droplets of water in the upper layers of air where it is cooler. True

4. Suppose you want to dry your school uniform quickly. Would spreading it near an anghiti or heater help you? If yes, how?
Ans: Yes, to dry the school uniform quickly, the uniform is spread near an anghiti or heater because evaporation is rapid at higher temperature. Higher the temperature faster is the rate of evaporation. So the uniform is dried up quickly.

5. Take out a cooled bottle of water from refrigerator and keep it on a table. After some time you notice a puddle of water around it. Why?
Ans: The cooled water bottle has very cold exposed surface. Due to cool surface there is condensation of water-vapour from air on the surface of water bottle because water vapour is present in atmosphere. The condensed water molecules spread around the bottle. So a puddle of water is noticed after sometime.

6.To clean their spectacles, people often breathe out on glasses to make them wet. Explain why the glasses become wet?
Ans: The breathe out gases contain water-vapour. The water-vapour condenses at spectacles so glass becomes wet and with the help of small amount of water, it is easy to clean the spectacles.

7. How are clouds formed?
Ans: The water present on the earth evaporates due to heating by the sun. The water vapour in the air condenses to form tiny droplets of water at high altitude, which appears as clouds. Thus clouds are formed by the condensation of water vapours present in air at high altitude.

8. When does a drought occur?
Ans: If there is no rain for a long period or for many years then there is scarcity of water in that region. This leads to drought.

Chapter 8 Let's Learn Scratch (Class 4)

Chapter 8

Let's Learn Scratch

E. Answer these questions.

1. What is a program?

Ans - The sequence of instructions given to a computer is called a program.

2. What is Scratch?

Ans - Scratch is a visual programming language used to create animations, games, stories and much more.

3. What is a Sprite?

Ans - Each object in Scratch, which is programmed to animate, is called a sprite.

4. What is Scripts/Code area?

Ans - Scripts/ Code area is the area where the code is written. A code is the collection of stepwise instructions that are given to a sprite to do a specific task.

Chapter 8 More About Scratch (Class 5)

 

Chapter 8
More About Scratch

E. Answer these questions.

1. What is Scratch?
Ans - Scratch is a graphical programming language developed by the Lifelong Kindergarten group at the MIT.

2. Define the following: 

(a) Sprite: 

Ans - Each object in Scratch which is programmed to animate is called a sprite. The Scratch cat is the default sprite in Scratch. We can change or add a new sprite.

(b) Backdrop:

Ans - Backdrop is the background of the stage in Scratch. Using backdrop, you can change the visual look of the stage area.

3. What is the use of Sprite Info pane?    
Ans - The Sprite Info pane, located below the Stage, displays detailed information about the sprites in a project. It display the thumbnails of all the sprites in the project.

4. What is the use of Events blocks?
Ans - Events blocks are used to control the events

 

 

Think and Tell  (page no. 105)

Describe the function of each block in short.

1. Ans - When the flag is clicked, the code runs

2. Ans - Controls direction in which a sprite can rotate in

3. Ans - On pressing specified key from the list, the code runs

Workbook Class 6 Science Chapter 11 Light, Shadows and Reflections

Chapter 11
Light, Shadows and Reflections

Exercise

I. Answer  the following questions in brief:

Q.1. What else is required to see a shadow besides a source of light and an opaque object?
Ans - When light falls on an opaque object a dark patch is formed on the other side of the object.

Q.2. Is the shape of the shadow of an object same as the shape of an object? If not, give an example proving so.
Ans - No, there is difference in the shape of the shadow as the object because it depends on the position of the sun. For example -
if we see our shadow in morning when sun rises or evening when sun sets our shadow is the largest at this time. 

Q.3. How is the image of an object taken from a pin-hole camera different from the object?
Ans - The image formed by a pinhole camera is inverted and smallest in size when compared to the original object. These cameras work on the principle that travels in a straight line. 

Q.4. Which property of light helps it to form shadows?
Ans - The reflection and rectilinear propagation of light helps in the formation of shadows.

Q.5. What does a mirror do to the direction of light that falls on it?
Ans - When light falls on a mirror, the direction of light changes.

Q.6. How is a shadow different from an image?
Ans - Image is the reflection of any object while shadow is the area of the object when light falls from a particular angle.

Q.7. Name any four things that can be used as screen for the formation of shadow or image.
Ans - (a) Opaque material , (b) Source of light.

Q.8. Given an activity to show that light travels in a straight line.
Ans - Fix a lighted candle on a table. Take a rubber tube, stretch it straight & look through it the name of the candle with one eye (keeping the other eye closed) we will find that when the rubber tube is straight we can see the light of candle flame through it.

 

II. Give one term for each of the following:

(a) Object through which light cannot pass at all. Opaque
(b) Figure formed when light bounces from a shiny surface. Reflected Ray
(c) Object which emits its own light  Luminous object
(d) Object through which we can see but not clearly. Translucent
(e) Figure formed when path of light is obstructed by an opaque object. Shadow


III. Fill in the blanks:

(a) We need a source of light, an Opaque object and a screen to form a shadow.
(b) Shadows can mislead us about the shape of the object.
(c) Light helps us see objects.
(d) Light travels in a straight line.
(e) Butter paper is a/an translucent object.
(f) The image formed by a pin-hole camera is real or inverted image.

IV. State whether True or False

(a) The shadow of an object gives us a clear idea about its shape and colour.   F
(b) Reflection of light is an indication that light travels in a straight line.   T
(c) Shadow and image are the same. F
(d) Light can travel through a bent pipe from one end to the other. F
(e) The image of the sun formed through a pin-hole camera is upside down.  T
(f) For the formation of a shadow, a source of light and an opaque object are enough.  F

V. Match the following:

(a) Reflection  - Mirror
(b) Rubbed glass   - Translucent
(c) Pinhole camera  - Upside down image
(d) Fire fly - Luminous
(e) Shadow - Opaque

VI. Select the correct alternative:

(i) Which of the following changes the direction of light that falls on it?
Ans - c) A mirror

(ii) In the activity shown below, light from the candle is not seen when the middle card board is moved sideways.

This activity shows that

Ans -b) Light travels in a straight line

(iii) What kind of object form shadows?

Ans - b) Opaque

(iv) Which of the following show that light travels in a straight line?

Ans - d) All of these

(v) Which of these are NOT needed for the formation of a shadow?

Ans - d) All of these are needed

NCERT Solutions for Class 6 Science Chapter 13 Fun with Magnets

Chapter 13

Fun with Magnets

1. Fill in the blanks in the following:

(i) Artificial magnets are made in different shapes such as bar magnets , horse-shoe magnets and  cylindrical magnets.

(ii) The materials which are attracted towards a magnet are called magnetic materials

(iii) Paper is not a magnetic.

(iv) In olden days, sailors used to find direction by suspending a piece of bar magnet.
(v) A magnet always has Two poles. 

2. State whether the following statements are true or false.

(i) A cylindrical magnet has only one pole. False
(ii) Natural magnets were discovered in Greece. False
(iii) Similar poles of a magnet repel each other. True
(iv) Maximum iron filings stick in the middle of a bar magnet when it is brought near them. False
(v) Bar magnets always point towards North-South direction when suspended freely in air. True
(vi) A compass can be used to find East-West direction at any place. True
(vii) Rubber is a magnetic material. False 

3. It was observed that a pencil sharpener gets attracted by both the poles of a magnet although its body is made of plastic. Name a material that might have been used to make some part of it.

Ans - The blade of a pencil sharpener is made of iron which is a magnetic material. Due to this a pencil sharpener gets attracted towards both poles of a magnet. 

4.  Column I shows different positions in which one pole of a magnet is placed near that of the other. Column II indicates the resulting action between them for each situation. Fill in the blanks.

Ans  -
Column I    Column II
N − N          Repulsion
N − S           Attraction
S − N          Attraction
S − S           Repulsion

5. Write any two properties of a magnet.

Ans - Two properties of a magnet are:
(i) A magnet always has two poles: North Pole and South Pole.
(ii) Like magnetic poles repel each other and unlike magnetic poles attract each other. 

6. Where are poles of a bar magnet located?

Ans - Poles of a bar magnet are located at its two ends.

7. A bar magnet has no markings to indicate its poles. How would you find out near which end is its north pole located?

Ans - Take the bar magnet and suspend it freely with the help of a thread, the end that points towards North Pole will be regarded as north end of the magnet. Take a bar magnet with known poles on it. Let the north pole of the magnet be brought closer to the suspended magnet at the end that is pointing towards north, if it show repulsion than it is conformed.

8. You are given iron strip. How will you make it into a magnet?

Ans - Making a magnet: Take an iron strip and place it on the table. Now take a bar magnet and place one of its poles near one edge of the strip of iron. Without lifting it moves it along the length of the iron strip till we reach the other end. Now lift the magnet and bring the pole to the same point of strip where we began. Repeat this process about 30-40 times. Bring some iron fillings near the strip and observe that the strip attracts the fillings. This indicates that the iron strip become magnet. 

9. How is compass used to find direction?

Ans - A compass is a small case of glass. A magnetised needle is pivoted inside the box. The needle can rotate freely. Compass also has a dial with directions marked on it. The compass is kept at the place where we want to know the directions. When needle comes to rest it indicates north-south direction. The compass is then rotated until the north and south marked on the dial are at the two ends of the needle.