English Medium Class 9 - CBSE Question Bank Solutions for Science

A piece of chalk can be broken into small particles by hammering but a piece of iron cannot be taken into small particles by hammering. Which characteristic of the particles of matter is illustrated by these observations?

What is the general name of :

1. rigid form of matter ?
2. fluid forms of matter ?

Fill in the following blank with suitable words :

The smell of perfume gradually spreads across a room due to .....................

State two characteristics of matter demonstrated by diffusion.

Explain why, we can easily move our hand in air but to do the same through a plank of wood, we need a karate expert.

Explain the following :

When an incense stick is lighted in the corner of a room, its fragrance spreads quickly in the entire room.

What are the common objectives of crop improvement?

What is meant by 'diffusion'? Give one example of diffusion in gases.

What we do get from cereals, pulses, fruits and vegetables?

Which one of the following statement is correct in respect of fluids?

In which of the following conditions, the distance between the molecules of hydrogen gas would increase?

1. increasing pressure on hydrogen contained in a closed container
2. some hydrogen gas leaking out of the container
3. increasing the volume of the container of hydrogen gas
4. adding more hydrogen gas to the container without increasing the volume of the container

Which of the following statement is incorrect?

Which one of the following statements is not true?

1. the molecules in a solid vibrate about a fixed position
2. the molecules in a liquid are arranged in a regular pattern
3. the molecules in a gas exert negligibly small forces on each other, except during collisions
4. the molecules of a gas occupy all the space available

Bromine particles are almost twice as heavy as chlorine particles. Which gas will diffuse faster; bromine (vapour) or chlorine? Explain your answer.

When a beam of sunlight enters a room through a window, we can see tiny particles X suspended in a gas (or rather a mixture of gases) Y which are moving rapidly in a very haphazard manner.

1. What could particles X be ?
2. Name the gas (or mixture of gases) Y.
3. What is the phenomenon exhibited by particles X known as ?
4. What is causing the movement of particles X ?
5. What conclusion does the existence of this phenomenon give us about the nature of matter ?

Explain the various methods of crop improvement. Name one improved variety of Rice, Maize, Soyabean, Sunflower and Mustard.

Write down differences between organ and organelle.

Differences between light microscope and electron microscope.

Give a brief account of discovery of the cell.

The mass of moon is about 0.012 times that of earth and its diameter is about 0.25 times that of earth. The value of G on the moon will be: