Draw a ray diagram to show the path of the reflected ray corresponding to an incident ray which is direct towards the principal focus of a convex mirror. Mark on it angle of incidence and the angle of reflection.

Name the method by which Hydra reproduces. Is this method sexual or asexual?

Define the following terms:

i. Valency

ii. Atomic size

What is meant by biodiversity? List two advantages of conserving forest and wildlife.

During the reaction of some metals with dilute hydrochloric acid, following observations were made.

i. The temperature of the reaction mixture rises when aluminium (Al) is added.

ii. The reaction of sodium metal is found to be highly explosive.

iii. Some bubbles of a gas are seen when lead (Pb) is reacted with the acid.

Explain these observations giving suitable reasons.