a) An electric bell is suspended by thin wires in a glass vessel and set ringing. Describe and explain what happens if the air is gradually pumped out of the glass vessel.b) Why cannot a sound be heard on the moon? How do astronauts talk to one another on the surface of moon?

I want  complete notes on the chapter friction 

In my book subtopics are:

Friction 

Types of friction 

Factors affecting friction 

Methods of reducing friction 

Methods of increasing friction 

Advantages and disadvantages of friction 

Some real life based situation where friction is applied.

How to make a monomer into polymer if it is an addition polymer example

This planet, _______ is yellowish in colour and has many rings and satellites.

A. Uranus

B. Jupiter

C. Neptune

D. Saturn

Pasteurized milk does not need to be boiled. Why?

Write the $pH$ value of the

1. Saliva (before meal)

2. Saliva (after meal)

3. Lemon juice

4. Colourless aerated drink

5. Carrot juice

6. Coffee

7. Tomato juice

8. Tap water