Combustion and flame — Science STD 8 — Question

What happens to the size of the pupil of our eye in bright light?

Name the most common application of the chemical effect of electric current.

Why even protected forests are not safe for wild animals?

What is the name of a small opening in the iris of an eye?

A is an insect which breeds in ponds of stagnant water. The egg of this insect produces a worm like form B which is entirely different in appearance from the adult insects. The form B undergoes a change C and gets converted into insects A. The female of insects A is a carrier of protozoan D which spreads a disease in humans.

1. What are A, B, C, and D?
2. Name another insect which also undergoes change C.

What is meant by dispersion of light? Name a natural phenomenon which is caused by the dispersion of sunlight in the sky.

Why do female frogs (or female fish) lay hundreds of eggs?

What do you understand by the term 'point of incidence'?

Whenever we push a very heavy box kept on the ground, it does not move at all because frictional force balances the force that we apply. So, there is no net movement of this box. It acts in a direction opposite to the force we apply.

What is an endocrine gland? Name two endocrine glands.