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(i) 4 × 3 × 2 = 24 

No. of cubes in the fig. = 24

(ii) 3 × 2 + 2 = 6 + 2 = 8 

No. of cubes in the fig. = 8

(iii) 3 + 2 + 2 + 1 + 1 = 9 

No. of cubes in the fig. = 9

i) Sum of the opposite faces = 2 + 1 = 3 

ii) Sum of the opposite faces = 3 + 4 = 7

Correct Answer is 

1) – b

2) – c 

3) – d 

4) – a

i) A Circle – Spherical/circular objects 

ii) A Square – Cube/square sheets 

iii) A Triangle – Triangular/right prism with triangular base 

iv) A Rectangle – Cuboid/rectangular shapes.

i) Cone : Ice-cream cone, birthday caps

ii) Cube : Die, chalk piece box

iii) Cuboid : Eraser, brick

iv) Sphere : Marbles, balls

v) Cylinder: Pencil, candle, pipe

1. A rainbow is a natural spectrum of sunlight in the form of bows appearing in the sky when the sun shines on raindrops after the rain. 

2. It is formed due to reflection, refraction and dispersion of sunlight by tiny water droplets present in the atmosphere

UV (ultraviolet) rays are very harmful to us. They damage the eyes as more than 99% of UV radiation is absorbed by the front of the eyes. It can lead to corneal damage, cataract, skin cancer, blindness. It also causes premature ageing of the skin, suppression of the immune system etc.

Correct option is B) Lodestone

Lodestone is a natural magnet.

Correct option is A) Bar

I found the following things in magnets to appreciate. 

1. Every magnet has two poles. If we break a magnet into two pieces, each piece develops two poles and act as individual magnets. 

2. A freely suspended magnet always rests in the north-south direction. This helps in identifying the directions in new places. 

3. Iron nail kept near magnet act as magnet due to magnetic induction. 

4. Magnetic levitation helps to run electro-magnetic trains.

5. The attraction property of magnets helps in the separation of magnetic materials from their mixtures. 

6. Electrical cranes are used to lift the huge weight of magnetic materials using this attraction property. 

7. Magnets are useful in various equipment such as motors, speakers, etc.

(b) Magnetite

1. Is there any big magnet present inside the Earth? 

2. Who has put that magnet inside the Earth? 

3. Where are the South and North poles of Earth’s magnet? 

4. How is this magnet inside the earth discovered? 

5. Is the magnet inside the earth there from the time of formation of the earth? Such questions are likely to be asked by Sreevidya.

By using a bar magnet, the magnetic substance is separated from mixture.

Electromagnets are used in doorbells, cranes, loudspeakers, voltameters, TVs, antennas, radios etc.

The magnet with known poles will attract and repeat two ends of a magnet and attend both the end of an ordinary bar. (Test for repulsion)

1. We will take a bar magnet. We have to identify two identical bars A and B. One as a magnet and the other as a simple bar. 

2. To identify, we have to bring our magnet to both the ends of bars A and B one after another. 

3. It is easy to locate the magnet. It attracts the bar magnet when pointed to its one end and repels if pointed to the other end. 

4. The iron bar will be attracted by the magnet in both situations.

Magnet comes to rest in N-S (North – South) direction.

Hint:
(1) By suspending the metal bars
(2) By attracting iron filings
(3) Using another magnet

There is repulsion between these two magnets as there is repulsion between like poles.

The pins are made of stainless steel which is a non/magnetic material.

By using a magnet. If it has iron powder they will stick on to the magnet.

1. Secure a plastic toy car. Fix a small bar magnet in it by using tape. 

2. Now, keep the car on a table and hold it in your hand. 

3. Keep the N-pole of the magnet facing the S-pole of the magnet in the toy car. 

4. The car moves forward as your gradually draw the magnet in your hand backwards. (∵ unlike poles of magnets attract each other)

1. Opposite poles of two magnet attract each other while like poles of two magnet repel each other.
2. A freely suspended magnet always aligns in N-S direction.

(1) The end of the magnet has more iron fillings attached to it.
(2) These regions are called poles of the magnet.

If the front of the toy car gets attracted to the north pole of the given magnet then it is the south pole of the bar magnet hidden inside the car.

Correct option is B) Non-magnetic

1. Magnet aligns in North-South direction when suspended freely. 

2. A magnet has two magnetic poles.

1. In the experiments with magnets, we need to use iron filings again and again. 

2. We can collect these by placing a magnet in a pile of sand and turning it around in the sand. 

3. The small pieces of iron present in the sand will stick to the magnet. 

4. If we cannot find sand we can look for iron pieces in clay soil as well. 

Plastic scale, a piece of glass, paper, pen, pencil, stainless steel spoon, piece of chalk, wood.

(d) In A, cars 1 and 2 will come closer to each other and in B, 3 and 4 will move away from each other.

1. A compass has a magnetic needle attached to it which can rotates freely. 

2. The magnet always points to N – S direction which is marked on compass and thus help in finding direction.

1. A magnetic compass is used to find directions. 

2. It is mostly used in ships and airplanes. 

3. Mountaineers and army people also carry a compass with them so that they do not lose their way in an unknown place.

Correct option is D) Magnetic, repulsion

i) The needle stand vertically up without touching the glass. 

ii) Yes. This is because the magnet in the glass is attracting the needle.

1. The compass needle is a small and thin magnet used to find the direction. 

2. If it is kept in open, it may deflect in any direction. 

3. So to know right direction, it is kept covered by glass covering.

The blade of sharpener is made up of Iron which is a magnetic substance which gets attracted by both the poles of a magnet although its body is made of plastic.

To locate its north pole, we would do the following steps : 

1. A bar is taken and suspended freely from the middle with the help of thread. 

2. Allow the magnet to comes into rest.

3. The North pole of the magnet will face the north direction and south pole will face the south direction. 

4. Mark the north pole of the magnet with the marker.

Correct option is C) Both are correct

A) a – 1, b – 2, c – 3

(i) True 

(ii) True 

(iii)  False

The correct answerm is C) heated.

(i) natural

(ii) Artificial magnets

(iii) Magnetite

(iv) lode stones

(v) magnetization

(vi) magnetic material

(i) directional

(ii) direction

(iii) magnetic induction

(iv) magnet

(v) magnetic