Simple Machines

Question 1:

Classify the following as a lever, a pulley and an inclined plane :
A wedge, a needle, a staircase, a slide, the wheel of a flagpole, nutcrackers, scissors, an opener, an axe, a crane, a knife.

ANSWER:

A wedge: An inclined plane
A needle: An inclined plane
A staircase: An inclined plane
A slide: An inclined plane
The wheel of a flagpole: A pulley
Nutcrackers: A lever
Scissors: A lever
An opener: A lever
An axe: An inclined plane
A crane: A pulley
A knife: An inclined plane

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Question 2:

Fill in the blanks using the proper word and complete the statements.
(a) The ....... in the centre, the .......... on one side and the ...... on the other side make a lever of the first order.
(b) The ..... in the centre, the ........ on one side and the ......... on the other side make a lever of the second order.
(c) The .......... in the centre, the ....... on one side and the........on the other side make a lever of the third order.

ANSWER:

(a) The fulcrum in the centre, the load on one side and the effort on the other side make a lever of the first order.
(b) The load in the centre, the fulcrum on one side and the effort on the other side make a lever of the second order.
(c) The effort in the centre, the load on one side and the fulcrum on the other side make a lever of the third order.

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Question 3:

Which machines will you use to do the following work? Write their types.
(a) To remove the lid of a tin.
(b) To lift bricks to the top of a tall building.
(c) To cut vegetables.
(d) To draw water from a well.
(e) To hold a papad for roasting it.

ANSWER:

(a) To remove the lid of a tin, we should use an opener which is a second order lever.

(b) To lift bricks to the top of a tall building, we should use a crane which is a pulley.

(c) To cut vegetables, we should use a knife which is a wedge.

(d) To draw water from a well, we should use a pulley system or wheel-axle.

(e) To hold a papad for roasting it, we should use a tong which is a third order lever.

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Question 4:

Write the answers to the following questions in your own words.
(a) What is meant by simple machines?
(b) Mention the advantages of using a machine.
(c) What is meant by complex machines?
(d) What is a lever ? How are the orders of the lever determined?

ANSWER:

(a) Simple machines are the tools that help people work faster and better. These help us lift heavy loads, change the speed of the motion or the direction of force. Examples are simple machines are knife, nutcrackers etc.

(b) The advantages of using a machine are:

• More work can be done in lesser time as well as with great accuracy
• Less effort has to be applied to accomplish the task

(c) A machine made up of two or more simple machines is called a complex machine. It consists of different parts that carry out different task and together contribute to the working of the machine. The most common example is that of a bicycle.

(d) A lever is a simple machine consisting of a rigid rod which is capable of turning around a pivot called a fulcrum. It has three parts, namely, effort, load and fulcrum.

• Fulcrum: The rod of the lever rests on it and the lever rotates about it.
• Load: The weight lifted by the liver is called the load.
• Effort: The force applied on the other end of the rod to lift the load is called the effort.

The orders of the lever are determined depending on the position of the effort, the fulcrum and the load.
Lever of first order: When the fulcrum is situated between load and effort, we call it a lever of first order. For example, beam balance, a crowbar, a see-saw.

Lever of second order: When the fulcrum and effort are situated at the two opposite ends of the lever and a load is placed in between them, we call it a lever of second order. For example, a nutcracker, a wheel-barrow, etc.

Lever of third order: When the fulcrum and load is situated at the opposite ends of the lever and an effort is applied somewhere between them, we call it a lever of third order. For example, a pair of tongs, a fishing rod, etc.

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Question 5:

Why is this so?
(a) Traveller’s bags have wheels.
(b) Machines have to be maintained.
(c) A bicyle is said to be a complex machine.

ANSWER:

(a) Traveller's bag has wheels so that it can be dragged easily because of reduced friction between the ground and the wheel. Thus, the wheel, a simple machine, helps to decrease the effort to be applied on the load which is a bag here.

(b) A machine is composed of many parts. These parts rub against one another when in use. Due to this, these parts wear out with time. Also, soil and dust creates more friction between the parts which further deteriorates their condition. Even, some parts get affected by weather and thus rust and erode. Because of these factors, the machine can become useless if proper care is not given to it. So, it is very necessary that we have proper equipments and methods for the maintenance of machines. Thus, machines should be sent for maintenance check at fixed interval of time to ensure their proper working.

(c) A bicycle is composed of many simple machines, such as a screw, wheel and axle, lever, pulley, which carry out different task and together contribute to its working. Thus, the bicycle is said to be a complex machine.

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Question 6:

Name the levers mentioned in the following passage. Identify the fulcrum, load and effort of each and say which type of lever it is.
Ravi and Savita sit on a sea-saw in a garden. In the mean time, a gardener is trimming trees in the garden. He puts the leaves and other garbage in the wheelbarrow. Later, Ravi gets thirsty and he buys lemon sherbet. The sherbet seller cuts the lemon and squeezes it using a lemon squeezer. He puts small pieces of ice in the glass with the help of the tongs

ANSWER:

Levers mentioned in the passage are:
(a) Sea-saw: It is a first order lever.

(b) Wheel barrow: It is a second order lever.

(c) Lemon squeezer: It is a second order lever.

Credit:www.meritnation.com

Substances in the surroundings-their states and properties .

Question 1:

In the paragraph below, write ‘solid’, ‘liquid’ or ‘gas’ in each of the brackets depending on the substance referred to just before.
On a bright sunny day, Riya and Gargi are playing with a ball (   ) in the park. Gargi feels thirsty. So, Riya brings tender coconut water (   ) for her. At the same time, a strong breeze (   ) starts blowing and it also begins to rain (   ). They run back into the house (   ), change their clothes (   ) and then their mother gives them a cup (   ) of hot milk (   ) to drink.

ANSWER:

On a bright sunny day, Riya and Gargi are playing with a ball (solid) in the park. Gargi feels thirsty. So, Riya brings tender coconut water (liquid) for her. At the same time, a strong breeze (gas) starts blowing and it also begins to rain (liquid). They run back into the house (solid), change their clothes (solid) and then their mother gives them a cup (solid) of hot milk (liquid) to drink.

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Question 2:

Discuss.
(a) Riya pours some water from her bottle into another bottle. Does it change the shape of the water ?
(b) Halima picks up a small stone from the ground and puts it in the water in a dish. Does the shape of the stone change ?

ANSWER:

a. Yes, the shape of the water will change because liquids do not have a shape of their own. They take the shape of the container in which they are present.

b. No, the shape of the stone will not change by putting it in a dish containing water because solids have definite shape. They do not change their shape and retain it, no matter whatever be the circumstances.

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Question 3:

Write the properties of these substances.
Water, glass, chalk, iron ball, sugar, salt, flour, coal, soil, pen, ink, soap.

ANSWER:

Water- Fluidity
Glass- Transparent, brittle
Chalk- Brittle
Iron ball- Hardness
Sugar- Solubility
Salt- Solubility
Flour-Solubility
Coal- Brittle
Soil- Solubility
Pen- Hard
Ink- Fluidity
Soap- Brittle

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Question 4:

What is sublimation? Write the names of everyday substances that sublimate.

ANSWER:

Sublimation is the change of the gaseous state directly into the solid state, without going through the liquid state, and vice versa. 
Examples of sublimation:- dry ice, moth balls or napthalene balls, camphor (kapur).

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Question 5:

What is it made from? Why?
(a) A sickle to cut sugarcane.
(b) The sheets used for roofing.
(c) A screwdriver
(d) A pair of tongs.
(e) Electric cables.
(f) Ornaments.
(g) Pots and pans.

ANSWER:

(a) A sickle to cut sugarcane- Made out of iron since it is very hard and strong.
(b) The sheets used for roofing- Aluminium is used to make sheets for roofing because it is malleable i.e. it can be hammered into sheets.
(c) A screwdriver- It is made up of steel beacuse it is very hard and duable.
(d) A pair of tongs- They are made up of metals like iron or aluminium beacuse they have high melting points and do not melt while using on flames.
(e) Electric cables- Metals like silver, gold, copper and platinum are used to make wires because they are ductile i.e. they can be drawn into wires.
(f) Ornaments- Metals such as gold and silver are used for making jewellery because they are very lustrous. 
(g) Pots and pans- Copper is used to make pots and pans because it is a good conductor of heat.
 

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Question 6:

What will happen if....? And why ?
(a) Nails are made of plastic.
(b) A bell is made of wood.
(c) Rubber is not fitted on a pair of tongs.
(d) A knife is made of wood.
(e) An axe is made of rubber.

ANSWER:

a. If nails are made out of plastic, they cannot be used for its usual purposes. They could not be hammered like iron nails and ould not possess the strength which iron nails have. It means they would have no strength to hold the things together.

b. If a bell is made of wood, it will not ring. The bells are made up of metals like copper etc. as they show the property of sonority i.e. the ability to produce a ringing sound when striked upon. Wood does not have this property and hence cannot be used to make bells.

c. Tongs are made up of metals and they have the ability to conduct heat. If rubber is attached to the tongs, the heat will be transfered to the rubber and it will melt off.

d. Knife is used to cut vegetables, fruits etc. The regular knifes which we use are made up of metals like iron etc. as they are hard, strong and durable. Also they can be sharpened and moulded into shapes which we desire. Knifes made out of wood cannot be used for cutting or chopping purposes.

e. An axe is used to cut and chop wood. It is made up of metals beacause they are stong, hard and durable. Also they can be moulded and sharpened which is an important characteristic. These properties are not applicable to rubber. An axe made of rubber will neither be hard nor sharp enough so that it can be used for its usual purposes.

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Question 7:

Who am I ?
(a) I’m found in a thermometer, I measure your temperature.
(b) I make things hot or cold.
(c) I have no shape whatsoever !
(d) I dissolve in water, but not in kerosene.

ANSWER:

(a) I’m found in a thermometer, I measure your temperature- Mercury
(b) I make things hot or cold- Temperature
(c) I have no shape whatsoever !- Gas
(d) I dissolve in water, but not in kerosene- Salt

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Question 8:

Why does this happen ?
(a) Coconut oil thickens in winter.
(b) Kerosene left open in a dish disappears.
(c) The fragrance of incense sticks lighted in one corner of a room spreads to the other corner.
(d) What you see in the picture.

ANSWER:

a. Coconut oil is made up of two types of fat- saturated and unsaturated fats. It contains 90% saturated fats and 10% unsaturated fats. It remains liquid at higher temperatures but turns into solid as the temperatures drop in winters. This property of coconut oil is attributed to the higher content of saturated fats. Oils like mustard oil, sunflower oil remain liquid even in winters because they contain less amount of saturated fats as compared to coconut oil.

b. Kerosene left open in a dish disappears because it is a volatile compound. It quickly evopurates if it is kept in open.

c. When the incense stick is lighted, it releases smoke which contains the fragrance. Smoke is a form of gas which quickly spreads in the entire room along with the fragrance and thus making the entire room fragrant.

d. The picture shows two things which are present in tub of water. One is a balloon which floats on the surface of the water while the other is an apple which sinks to the bottom of the tub. The balloon floats on the surface of the water because it has less denity as compared to the density of the water whereas the apple sinks to the bottom of the tub because it has more density than water.

Algebraic Expressions

1.Classify the following algebraic expressions as monomials, binomials, trinomials or  polynomials.

(i) 7x  (ii) 5y −$-$ 7z (iii) 3x³ −$-$5x² −$-$11    (iv) 1 −$-$8a−$-$7a ²−$-$7a³

(v) 5m−$-$3 (vi) a (vii) 4

(viii) 3y²−$-$7y + 5

ANSWER:

It is known that, expressions with one term is called monomial, expressions with two terms are binomials, expressions with three terms are trinomials and expression with more than three terms are polynomials.
(i) 7x = Monomial
(ii) 5y−$-$7z = Binomial
(iii) 3x³−$-$5x²−$-$11 = Trinomial
(iv) 1−$-$8a−$-$7a²−$-$7a³ = Polynomial
(v) 5m−$-$3 = Binomial
(vi) 4 = Monomial
(vii) 3y²−$-$7y+5 = Trinomial

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Question 1:

Add.

(i) 9p + 16q ; 13p + 2q       (ii) 2a + 6b + 8c; 16a + 13c+ 18b  
(iii) 13x²−$-$12y² ; 6x² −$-$ 8y²        (iv) 17a² b² + 16c ; 28c −$-$ 28a² b²
(v) 3y² −$-$ 10y + 16 ; 2y−$-$7 ​       (vi) −$-$3y² + 10y  −$-$16 ; 7y² + 8

 

 

ANSWER:

(i) (9p + 16q) + (13p + 2q)
= 9p + 16q + 13p + 2q
=(9p + 13p) + (16q + 2q)
=22p + 18q

(ii) (2a + 6b + 8c) + (16a + 13c + 18b)
= 2a + 6b + 8c + 16a + 13c + 18b
= (2a + 16a) + (6b + 18b) + (8c + 13c)
= 18a + 24b + 21c

(iii) (13x² − 12y²) + (6x² − 8y²)
= 13x² − 12y² + 6x² − 8y²
= (13x² + 6x²) + (−12y² − 8y²)
=19x² + (−20y²)
=19x² − 20y²

(iv) (17a²b² + 16c) + (28c − 28a²b²)
= 17a²b² + 16c + 28c − 28a²b²
= (17a²b² − 28a²b²) + (16c + 28c)
= −11a²b² + 44c

(v) (3y² − 10y + 16) + (2y − 7)
= 3y² − 10y + 16 + 2y − 7
= 3y² + (−10y + 2y) + (16 − 7)
=3y² + (−8y) + 9
=3y² − 8y + 9

(vi) (−3y² + 10y − 16) + (7y² + 8)
= −3y² + 10y − 16 + 7y² + 8
= (−3y² + 7y²) + 10y  + (−16 + 8)
= 4y² + 10y + (−8)
= 4y² + 10y − 8

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Question 1:

Subtract the second expression from the first.

(i)  (4xy−9z) ; (3xy −16z) (ii)  (5x + 4y + 7z) ; (x + 2y + 3z)

(iii) (14x² + 8xy + 3y² ) ; (26x² − 8xy− 17y²)  (iv) (6x²+ 7xy+ 16y² ) ; (16x² − 17xy)

(v) (4x + 16z) ; (19y −14z + 16x)

ANSWER:

(i) (4xy − 9z) − (3xy − 16z)
= 4xy − 9z − 3xy + 16z
= (4xy − 3xy) + (16z − 9z)
= xy + 7z

(ii) (5x + 4y + 7z) − (x + 2y + 3z)
= 5x + 4y + 7z − x − 2y − 3z
= (5x − x) + (4y − 2y) + ( 7z − 3z)
= 4x + 2y + 4z

(iii) (14x² + 8xy + 3y²) − (26x² − 8xy − 17y²)
= 14x² + 8xy + 3y² − 26x² + 8xy + 17y²
= (14x² − 26x²) + (8xy + 8xy) + (3y² + 17y²)
= −12x² + 16xy + 20y²

(iv) (6x²+ 7xy+ 16y² ) − (16x² −$-$ 17xy)
= 6x² + 7xy + 16y² − 16x² +17xy
= (6x² − 16x²) + (7xy + 17xy) + 16y²
= −10x² + 24xy + 16y²

(v) (4x + 16z) − (19y − 14z + 16x)
= 4x + 16z − 19y + 14z − 16x
= (4x − 16x) + (16z + 14z) − 19y
= −12x + 30z − 19y

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Question 1:

Multiply.

(i) 16xy × 18xy (ii) 23xy² × 4yz² 

(iii) (12a + 17b) × 4c  (iv) (4x + 5y) × (9x + 7y)

ANSWER:

(i) 16xy × 18xy
= 16 × 18 × x × y × x × y
= 288x²y²

(ii) 23xy² × 4yz²
= 23 × 4 × x × y² × y × z²
= 92xy³z²

(iii) (12a + 17b) × 4c
= 12a × 4c + 17b × 4c
= 12 × 4 × a × c + 17 × 4 × b × c
= 48ac + 68bc

(iv) (4x + 5y) × (9x + 7y)
= 4x(9x + 7y) + 5y(9x + 7y)
= 4x × 9x + 4x × 7y + 5y × 9x + 5y × 7y
= 36x² + 28xy + 45xy + 35y²
= 36x² + 73xy +35y²

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Question 2:

A rectangle is (8x + 5) cm long and (5x + 3) cm broad. Find its area.

ANSWER:

Length of the rectangle = (8x + 5) cm
Breadth of the rectangle = (5x + 3) cm
Area of rectangle = length × breadth
= (8x + 5)(5x + 3)
= 8x(5x + 3) + 5(5x + 3)
= 8x × 5x + 8x × 3 + 5 × 5x + 5 × 3
= 40x² + 24x + 25x + 15
= 40x² + 49x + 15
So, area of rectangle is (40x² + 49x + 15) cm².

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Question 1:

Simplify (3x −11y)−(17x  + 13y) and choose the right answer.

 

(i) 7x −12y  (ii) −14x −$-$54y (iii) −3 (5x  + 4y )     (iv) −2 (7x + 12y )

ANSWER:

(3x − 11y) −(17x  + 13y)
= 3x −11y −17x −13y
= (3x − 17x) + (−11y −13y)
= −$-$14x + (−24y)
= −14x − 24y
= −2(7x + 12y)
So, the correct option is (iv).
 

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Question 2:

The product of (23 x² y³ z) and ( −15x³ yz² ) is .................... .

 

(i) −345  x⁵ y⁴ z³   (ii) 345  x² y³ z⁵   (iii) 145 x³y² z    (iv) 170 x³y² z³

ANSWER:

(23x²y³z) × (−15x³yz²)
= 23 × (−15) × x² × y³ × z × x³ × y × z²
= −345x⁵y⁴z³
So, the correct option is (i)

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Question 4:

Rakesh’s age is less than Sania’s age by 5 years. The sum of their ages is 27 years. How old are they?

ANSWER:

Let the age of Sania = x years
Then, the age of Rakesh = (x − 5) years
According to question, sum of ages of Sania and Rakesh is 27 years.
∴ x+(x−5)=27⇒x+x−5=27⇒2x−5=27⇒2x=27+5⇒2x=32⇒x=16$$\begin{gathered} \therefore x+\left(x-5\right)=27 \\ \Rightarrow x+x-5=27 \\ \Rightarrow 2x-5=27 \\ \Rightarrow 2x=27+5 \\ \Rightarrow 2x=32 \\ \Rightarrow x=16 \end{gathered}$$
So, age of Sania = x years = 16 years
age of Rakesh = (x − 5) years = (16 − 5) years = 11 years

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Question 5:

When planting a forest, the number of jambhul trees planted was greater than the number of ashoka trees by 60. If there are altogether 200 trees of these two types, how many jambhul trees were planted ?

ANSWER:

Let the number of ashoka trees planted in the forest = x
Then, the number of jambhul trees planted in the forest = x + 60
According to question, total number of ashoka and jambhul trees planted in the forest is 200.
⇒x + (x+60)=200⇒x+x+60=200⇒2x+60=200⇒2x=200−60⇒2x=140⇒x=1402⇒x=70$$\begin{gathered} \Rightarrow x + \left(x+60\right)=200 \\ \Rightarrow x+x+60=200 \\ \Rightarrow 2x+60=200 \\ \Rightarrow 2x=200-60 \\ \Rightarrow 2x=140 \\ \Rightarrow x=\frac{140}{2} \\ \Rightarrow x=70 \end{gathered}$$
Number of ashoka trees planted in the forest = x = 70
Number of jambhul trees planted in the forest = x + 60 = 70 + 60 = 130

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Question 6:

Shubhangi has twice as many 20-rupee notes as she has 50-rupee notes. Altogether,she has 2700 rupees. How many 50-rupee notes does she have ?

ANSWER:

Let the number of 50-rupee notes = x
Then, the number of 20-rupee notes = 2 × number of 50-rupee notes = 2x
Amount of 50-rupee notes = Rs(50 × x) = Rs 50x
Amount of 20-rupee notes = Rs(20 × 2x) = Rs 40x
It is given that total amount is Rs 2700.
∴ 50x+40x=2700⇒90x=2700⇒x=270090⇒x=30$$\begin{gathered} \therefore 50x+40x=2700 \\ \Rightarrow 90x=2700 \\ \Rightarrow x=\frac{2700}{90} \\ \Rightarrow x=30 \end{gathered}$$
Number of 50-rupee notes = x = 30
Number of 20-rupee notes = 2x = 2 × 30 = 60

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Question 7:

Virat made twice as many runs as Rohit. The total of their scores is 2 less than a double century. How many runs did each of them make ?

ANSWER:

Let the runs scored by Rohit = x
The, the runs scored by Virat = 2 × runs scored by Rohit = 2x
According to question, total of their scores is 2 less than a double century.
∴ x+2x=200−2⇒3x=198⇒x=1983⇒x=66$$\begin{gathered} \therefore x+2x=200-2 \\ \Rightarrow 3x=198 \\ \Rightarrow x=\frac{198}{3} \\ \Rightarrow x=66 \end{gathered}$$
So, runs scored by Rohit = x = 66
Runs scored by Virat = 2x = 2 × 66 = 132

Disaster Management

Question 1:

What are the emergency contact numbers of the following?
(a) Police Control Room
(b) Fire brigade
(c) Ambulance
(d) National level single emergency number for disaster relief.

ANSWER:

(a) 100 should be dialled for Police control room.
(b) 101 should be dialled for Fire brigade.
(c) 102 should be dialled for Ambulance.
(d) 108 should be dialled for National level single emergency number for disaster relief.

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Question 2:

What first aid will you provide in the following situations?
(a) Dog bite
(b) Scratches/ bleeding
(c) Burns/scalds
(d) Snakebite
(e) Sunstroke

ANSWER:

(a) Following first aid should be provided for dog bite:

• A dog bite wound must be very thoroughly cleaned, first with soapy water and then with an antiseptic.

• If this is not done, the bite might lead to rabies.

• Cover the wound with a bandage.

• See a doctor immediately.

(b) Following first aid should be provided for scratches/bleeding:

• Clean the wound with cotton soaked in antiseptic lotion.

• Apply bandage (in case of a smaller wound) or antiseptic lotion and wrap with a bandage (in case of a bigger wound).

• In case of heavy bleeding, tie a handkerchief above the wound to stop bleeding.

​(c) Following first aid should be provided for burns/scalds:

Minor Burns:

• Pour plenty of cold water immediately over it.

• Apply an anti-burn ointment.

• Immediate home remedies:

  •  Apply baking soda mixed with water

  • Apply the paste of turmeric and milk

  • Apply the paste of raw potato

Severe Burns:

• In case clothes of a person catch fire, cover the person with a blanket and make the person roll over the ground in order to put out the fire.

• Make the person lie down in an open space.

• Remove the burnt clothes that are not sticking to the body.

• Give him plenty of water to drink.

• Apply anti-burn ointment on the burn.

​(d) Following first aid should be provided for snakebite:

• Keep the person calm and restrict any movement.

• Do not make him eat or drink anything.

• Tightly tie a handkerchief above the bite to prevent the poison from spreading and reaching the heart or the nervous system.

• Seek medical attention immediately.

​(e) Following first aid should be provided for sunstroke:

• Make the person sit in the shade or a cool place.

• Cover the body with cool damp sheets.

• Make the person drink plenty of water or liquids.

• Apply cooling measures like ice towels.

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Question 3:

Write the causes of the following :
(a) Floods
(b) Forest fires
(c) Land slides/building collapse
(d) Storms
(e) Earthquakes

ANSWER:

(a) Following can be the cause of floods in a region:

• It may occur due to heavy rainfall that leads to overflow of water from the water bodies.
• Sudden melting of huge amount of ice at mountain tops can lead to flood in the regions nearby to mountains.
• Cloudburst can lead to flood.

​(b) Following can be the cause of forest fires:

• Natural calamities like lightning strikes falling on the trees of a forest.
• Man made activities like smoking, setting thermal factories or campfires near the forest area, etc.

(c) Landslide/building collapse can occur due to following reasons:

• Earthquake can cause landslide and building collapse.
• Volcanic eruption can cause landslide.
• Usage of poor quality material for construction of building can lead to its collapse.
• Mining and weathering can cause landslides.

(d) Storms can occur either naturally or due to ecological imbalance occuring due to various human activities.
 
(e)  Earthquakes can occur due to following reasons:

• Volcanic eruption

• Meteors falling on the Earth’s surface

• Underground explosions. For example, underground nuclear tests.

• Collapsing structures such as mines etc.
   
• ​Mining and construction of big dams.

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Question 4:

Answer the following questions.
(a) What is meant by ‘disasters’?
(b) What are the types of disasters?
(c) What is meant by ‘disaster management’?
(d) Which are the main components of disaster management?

ANSWER:

(a) A sudden happening that causes enormous damage to life, property and social aspects of a nation or society is called a disaster.

(b) Disasters are of two types:
Man-made disasters: These disasters are the result of technological or human hazards. Examples of man-made disasters are road accidents, forest fires, collapsing of building due to usage of poor quality materials, etc.
Natural disasters: There are due to imbalance occurring in nature various environmental factors. Examples of natural disasters are earthquakes, volcanic eruption, etc.

(c) Disaster management is the strategy and course of action to be executed at the time of any disaster to save as much life as possible. 

(d) Main components of disaster management are:
Preparation: A plan is created to minimise the damage if a disaster occurs.
Redemption: It is the plan to minimise the damage to the society and country.
Preparedness: A plan is chalked out to get quick response from public and administration.
Impact of disaster: Intensity of disaster and disaster management are reviewed.
Response: This stage deals with providing immediate response after an incident has occurred.
Resurgence: It is an important link between emergency measures and national progress. It includes the steps which are required for the welfare and rehabilitation of the nation. 
Restoration: It is an important link between measures after disaster and national development. It includes steps useful for progress of
nation and rehabilitation.

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Question 5:

Find out about the work of a ‘Sarpa-mitra’.

ANSWER:

Sarpamitra (friend of snake) protects and safeguards snakes. They also demonstrate to people the various aspects of snakes and snake bites, what precautions and first-aid should be given in case of snake bite and the general idea of how to classify the snakes into poisonous and non-poisonous.

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Question 6:

Find out what a first aid kit/box contains.

ANSWER:

First aid box should contain the following things:

• First-aid manual
• Sterile gauze pads of different sizes
• Adhesive tape
• Adhesive bandages in several sizes
• Elastic bandage
• A splint
• Antiseptic wipes
• Soap
• Antibiotic ointment
• Antiseptic solution (like hydrogen peroxide)
• Hydrocortisone cream (1%)
• Extra prescription medications
• Tweezers
• Sharp scissors
• Safety pins
• Disposable instant cold packs
• Calamine lotion
• Alcohol wipes or ethyl alcohol
• Thermometer
• Tooth preservation kit
• Plastic non-latex gloves (at least 2 pairs)
• Flashlight and extra batteries
• A blanket
• Mouthpiece for administering CPR (can be obtained from your local Red Cross)
• List of emergency phone numbers

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Question 7:

Suggest remedial measures for dealing with natural or man-made disasters.

Disaster	Remedy	Disaster	Remedy
Fire		Earthquake
Building collapse		Deluge
Road accident		Storm
Flood		Tsunami
War		Drought
Bomb explosion		Landslide

ANSWER:

Disaster	Remedy	Disaster	Remedy
Fire	Call fire brigade, use fire extinguisher	Earthquake	Give help to clear debris, call ambulance to send victims to hospitals
Building collapse	Give help to clear debris, call ambulance to send victims to hospitals	Deluge	Donate food and clothing for flood victims, stay at some height if possible
Road accident	Call ambulance, give immediate first-aid and emotional support	Storm	Provide shelter and help in clearing the debris
Flood	Donate food and clothing for flood victims, stay at some height if possible	Tsunami	Move to a safer place, donate food and clothing for victims
War	Give shelter to innocent victims, provide food and clothing and first-aid to the victims	Drought	Donate food and water for victims, provide shelter and monetary help
Bomb explosion	Call ambulance, take the victims to a safer place and provide basic first-aid	Landslide	Help in rehabilitation services

Ch.2 The Living World

Question 1:

Write the answers to the following questions in your own words.
(a) What are the differences between plants and animals ?
(b) What are the similarities between plants and animals ?
(c) How is the plant kingdom useful to us ?
(d) How is the animal kingdom useful to us ?
(e) What makes living things different from non-living things ?

ANSWER:

a. 

Plants	Animals
They can make their own food by the process of photosynthesis. They are autotrophs.	They cannot make their own food. They are heterotrophs.
They show movement, but cannot show locomotion i.e., they cannot change their position from one place to another.	They show movement as well as locomotion.
They show response to stimuli, but lack sense organs.	They also show response to stimuli and have well-developed sense organs.
They grow throughout their life.	They stop growing once they reach their adult form.

b. Apart from various differences, plants and animals also have some similarities. Plants and animals both show vital processes like growth, reproduction, respiration and excretion. Both of them require energy to carry out their various functions.


c. The plant kingdom has various uses in our life like:

• they provide habitat for a variety of organisms.
• they are the major producers of oxygen.
• they provide us with wood, that is a source of fuel and other products.
• they provide us with plants that have medicinal and ornamental importance.

d. The animal kingdoms is useful to us in various ways. The animals from the animal kingdom can be domesticated for various purposes. There are three categories of useful domesticated animals.

• Milk and Flesh Yielding Animals- These are the animals from which we obtain food products. They include cattle, goat, poultry, pig, sheep, etc.

• Draught Animals- These are the animals used for transportation, ploughing of fields, and other agricultural activities. They are hardy and can lift heavy loads.

• Fibre, Hide, and Skin Yielding Animals- These animals yield useful products such as fibre (wool), hide, etc. They include sheep, goat, cattle, camel, etc.

e. 

Living things	Non-living things
They are made up of cells.	They are not made up of cells.
They show movement, but the energy for movement comes from within the organism.	They show movement by taking external force or energy.
They require food.	They do not require food.
Growth in them is irreversible.	Growth is reversible.
Respiration occurs in which food is oxidised to release energy.	They do not require respiration.
Reproduction occurs in living things.	Non-living things do not reproduce.

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Question 2:

What helps them to breathe ?

(a) A fish	(b) A snake
(c) A crane	(d) An earthworm
(e) Man	(f) A banyan tree
(g) A caterpillar

ANSWER:

(a) A fish- Gills
(b) A snake- External nares (they are similar to nose in humans)
(c) A crane- Nostrils
(d) An earthworm- Skin
(e) Man- Nose
(f) A banyan tree- Microscopic pores on leaves
(g) A caterpillar- Tiny holes on their body known as spiracles

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Question 3:

Fill in the blanks with the proper words from the brackets.
(a) The process by which plants make their own food is called ............ .
(b) To inhale ......... and to exhale ........ is called respiration.
(c) The elimination of waste substances from the body is called ............ .
(d) The ability to respond to an event is called ..... to ...... .
(e) On completing their lifespan, every living thing ........ .
(oxygen, dies, excretion, carbon dioxide, responsiveness, photosynthesis, stimuli)

ANSWER:

(a) The process by which plants make their own food is called photosynthesis.
(b) To inhale oxygen and to exhale carbon dioxide is called respiration.
(c) The elimination of waste substances from the body is called excretion.
(d) The ability to respond to an event is called responsiveness to stimuli.
(e) On completing their lifespan, every living thing dies.
(oxygen, dies, excretion, carbon dioxide, responsiveness, photosynthesis, stimuli)

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Question 4:

Write the uses of these animals and plants.
Animals : Honeybees, sharks, yaks, sheep, earthworms, dogs, bivalves, horses, mice.
Plants : Ginger, mango, eucalyptus, babul (acacia), teak, spinach, aloevera, turmeric, holy basil, karanja , moh , mulberry, grapevine.

ANSWER:

Animals	Uses
1. Honeybees	Provide us with honey and wax.
2. Sharks	Used in medicines, cosmetics, pet products etc.
3. Yaks	Used for obtaining wool.
4. Sheep	Used for obtaining wool.
5. Earthworm	Used in agriculture for composting(vermicomposting).
6. Dogs	As pets.
7. Bivalves	Used as a source of food.
8. Horses	For transportation.
9. Mice	As pets and models for testing various experiments.

Plant	Uses
1. Ginger	Used in foods and for medicinal purposes.
2. Mango	For obtaining fruits.
3. Eucalyptus	For making paper and essential oils.
4. Babul (Acacia)	Used in tooth pastes and other medicinal purposes.
5. Teak	Used in making furnitures.
6. Spinach	Used as food.
7. Aloe vera	Used for cosmetic and medicinal purposes.
8. Turmeric	Used as a spice and for various medicinal purposes.
9. Holy basil	Spiritual importance and for various medicinal purposes.
10. Karanja	Used for medicinal purposes like treating skin diseases.
11. Moh	Used for medicinal purposes.
12. Mulberry	For obtaining fruits.
13. Grapevine	For obtaining fruits and making wine.

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Question 5:

What are the peculiarities of the movements of these living things ?
Living things : Snakes, tortoises, kangaroos, eagles, chameleons, frogs, gulmohur, sweet potato creeper, dolphins, ants, rattlesnakes, grasshoppers, earthworms.

ANSWER:

Living thing	Movement
1. Snakes	Crawl
2. Tortoises	Swim and crawl
3. Kangaroos	Jump
4. Eagles	Fly
5. Chameleons	Walk
6. Frogs	Swim and hop
7. Gulmohar	Grows in the direction of light
8. Sweet potato	Grows in the direction of gravity
9. Creeper	Grows in the direction of light
10. Dolphins	Swim using fins
11. Ants	Walk
12. Rattlesnakes	Crawl
13. Grasshoppers	Hops
14. Earthworm	Crawl

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Question 6:

Write in detail about how the plants and animals found in your surroundings prove useful or harmful.

ANSWER:

There are so many kinds of plants and animals which we find in our surroundings. These plants and animals can be both useful and harmful to us. The follwoing points support this fact:

Useful plants:

• Plants like tulsi, mint, ashwagandha, neem etc. are called medicinal plants and have various medicinal properties.
• There are many plants which provide us with fruits and vegetables like mango etc.
• Certain plants are used for ornamental purposes like money plant etc.
• There are plants from which we obtain rubber which is used in the manufacture of tiers, tubes, raincoats, belts, sports goods, etc.
• Flowers like rose, jasmine, lavender, champa, saffron etc. are used for extracting sweet smelling oils called perfumes.

Harmful plants:

• Partehnium is a type of plant which can cause pollen allergy to humans.
• White Cedar is a small neem-like tree with attractive yellow fruits. These are lethal if taken by children and cause vomiting, diarrhea and difficulty in breathing in adults.
• Leaves of colocasia and pods of nettle cause itching.
• Datura is an example of poisnous plants.

Useful animals

• Milk and Flesh Yielding Animals- These are the animals from which we obtain food products. They include cattle, goat, poultry, pig, sheep, etc.
• Draught Animals- These are the animals used for transportation, ploughing of fields, and other agricultural activities. They are hardy and can lift heavy loads.
• Fibre, Hide, and Skin Yielding Animals- These animals yield useful products such as fibre (wool), hide, etc. They include sheep, goat, cattle, camel, etc.

All animals and insects are not useful, some of them can cause a lot of harm to our health and also to our crops. Such animals and insects are known as pests.

• Insects, like grasshoppers, beetles etc. cause enormous damage to the agricultural crops and thus affect their yield.
• Animals like tigers, lions etc. can enter human settlement and may kill domestic animals and people.
• Caterpillars or larvae of many insects feed on the leaves on which they live.
• Stored grains are also attacked by rodents like rats and rabbits and by many kind of moths, caterpillars and beetles.