English Medium इयत्ता ९ - CBSE Question Bank Solutions

Explain by an example what is meant by potential energy. Write down the expression for gravitational potential energy of a body of mass m placed at a height h above the surface of the earth.

What is the difference between gravitational potential energy and elastic potential energy? Give one example of a body having gravitational potential energy and another having elastic potential energy.

If 784 J of work was done in lifting a 20 kg mass, calculate the height through which it was lifted. (g = 9.8 m/s²)

When a ball is thrown vertically upwards, its velocity goes on decreasing. What happens to its potential energy as its velocity becomes zero?

A man is instructed to carry a package from the base camp at B to summit A of a hill at a height of 1200 metres. The man weighs 800 N and the package weighs 200 N. If g = 10 m/s²,

1. how much work does man do against gravity?
2. what is the potential energy of the package at A if its is assumed to be zero at B?

A car is accelerated on a levelled road and acquires a velocity 4 times of its initial velocity. During this process, the potential energy of the car :

Write the full form of IUPAC.

Name the three subatomic particles present in an atom.

What is the usual symbol for (a) and electron (b) a proton, and (c) a neutron?

What are the building blocks of matter ?

How is the size of an atom indicated ?

Name the unit in which the radius of an atom is usually expressed.

Write the relation between nanometre and metre.

Why is it not possible to see an atom even with the most powerful microscope ?

State whether the following statement is true or false :
The cathode rays obtained from all the gases consist of negatively charged particles called electrons.

Fill in the following blanks with suitable words :

In water, the proportion of oxygen and hydrogen is .............. by mass.

How many times is a proton heavier than an electron?

What value has been given to the mass of this reference atom ?

Dalton's atomic theory says that atoms are indivisible. Is this statement still valid ? Give reasons for your answer.

Is it possible to see atoms these days ? Explain your answer.