Matter in Our Surroundings — Science STD 9 — Question

On what factor/factors does the weight of a body depend?

Each beehive consists of thousands of hexagonal thin-walled fragile cells. Name the material which is used to make these cells and mention the significance of the hexagonal shape of the cell.

Name a basic tissue which is present in plants but absent in animals.

How does roughage differ from concentrates with reference to cattle feed?

Where do the ribosomes get synthesized?

The number of protons, neutrons and electrons in particles A to E are given below:

Particle	Protons	Neutrons	Electrons
A	17	18	17
B	3	4	2
C	18	22	18
D	17	20	17
E	9	10	10

Give reasons, find a pair of isotopes from the above particles.

Name an animal which navigates and find food by echolocation.

Name these force:
The force which wears away two surfaces as they move over one another.