A given sound is inaudible to the human ear, if (a) its amplitude is too small. (b) its frequency is below 20 Hz. (c) its frequency is above 20 kHz. (d) it has any of the three characteristics listed above.

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