21.

Which one of the following places in India is most likely to be affected by cyclones?

• Udaipur

• Badrinath

• Puri

• Amritsar

The air near a heat source gets hot and rises. The air from the sides comes into taking its place. This is the way in which the air gets heated by oil heaters. What is this process called?

• Convection

• Radiation

• Diffusion

• Conduction

A book is lying at rest on the surface of a table. Which one of the following statements is true about the force (s) acting on it?

• There is a pair of balanced forces acting on it

• Only gravitational force is acting on it

• Only frictional force is acting on it

• There is no force acting on it

Read the given statements and select the correct option.

1. The husk is separated from heavier seeds of grain by winnowing.
2. The difference in the size of particles in a mixture is utilised to separate them by the process of sieving and filtration.

• Statement Bis true and Statement A is false

• Both Statements A and B are false

• Both Statements A and Bare true

• Statement A is true and Statement Bis false

The pressure in a fluid that is at rest

• acts only in downward direction

• acts only sideways

• acts in all directions

• acts only in vertical direction

Which of the following statements are true about image formation in a plane mirror?

1. The image is larger in size than the object.
2. The image is formed at the same distance as the object
3. The image is laterally inverted
4. The image is virtual.

• B, C and D

• A, C and D

• All of these

• A, B and C

All of the following are single-celled, except

• embryo

• paramecium

• hen's egg

• zygote

Read the following examples from daily life and select the appropriate option.

1. When food gets spoiled, it produces a foul smell.
2. A slice of apple acquires brown colour when kept out for some time.
3. When an ant bites, calamine is used to ease the irritation on the skin.

• B is a physical change

• A and B are physical changes

• All are chemical changes

• A and B represent chemical changes

A student burns a magnesium ribbon in air and dissolves the ash of the ribbon left after burning in distilled water. On pouring one drop each of this solution, first in blue litmus and then in red litmus solution, he would observe that

• blue litmus turns red, whereas the red litmus remains red

• blue litmus turns red, whereas the red litmus turns blue

• blue litmus turns colorless, whereas the red litmus remains red

• blue litmus remains blue, whereas the red litmus turns blue

"Copper cannot displace zinc from its salt solution. Give the reason."

The following reasons are given by Class VIII students

1. Copper is more reactive than zinc.
2. Copper is less reactive than zinc.
3. Zinc is one of the noble metals.
4. Zinc appears below copper in reactivity series.

Select the correct reason(s) from the reasons given by Class VIII students.

• Only A

• C and D

• Only B

• A and D