chemical reactions and equations — Science STD 10 — Question

What is the angle of reflection when a ray of light falls normally on a mirror?

Improvement in our lifestyle have resulted in generation of greater amount of waste material. We use more and more disposable things due to our changed lifestyle and wrong attitude.
Questions :
(1) Name the two factors that have contributed to the deterioration of our environment.
(2) Why do we generate lot of waste now-a-days?
(3) Why most of the wastes from our homes contain more and more non-biodegradable substances?

What is called metallic lustre?

Define:
Rock salt

Why do you think the noble gases are placed in a separate group?

Would you be able to check if water is hard by using a detergent?

State any two examples of movement in order to protect ourselves.

What is the minimum distance between an object and its real image in case of a concave mirror?

Give an example of a plant hormone that promotes growth.

Name the three main common refractive defects of vision.