English Medium Class 9 - CBSE Question Bank Solutions

Is it possible that an object is in a state of accelerated motion due to external force acting on it, but no work is being done by the force? Explain it with an example.

If an electric iron of 1200 W is used for 30 minutes every day, find electric energy consumed in the month of April.

A light and a heavy object have the same momentum. Find out the ratio of their kinetic energies. Which one has larger kinetic energy?

Four men lift a 250 kg box to a height of 1 m and hold it without raising or lowering it.

(a) How much work is done by the men in lifting the box?

(b) How much work do they do in just holding it?

(c) Why do they get tired while holding it? (g = 10 m s^–2)

Define watt. Express kilowatt in terms of joule per second. A 150 kg car engine develops 500 W for each kg. What force does it exert in moving the car at a speed of 20 ms^–1?

Which one of the following causes kala-azar?

Why does a desert cooler cool better on a hot dry day?

How does water kept in an earthen pot (matka) become cool during summer?

Why does our palm feel cold when we put some acetone or petrol or perfume on it?

Why are we able to sip hot tea or milk faster from a saucer than a cup?

What type of clothes should we wear in summer?

What produces more severe burns, boiling water or steam?

How many atoms are present in a H₂S molecule?

On the basis of Rutherford’s model of an atom, which subatomic particle is present in the nucleus of an atom?

What do you think would be the observation if the α-particle scattering experiment is carried out using a foil of a metal other than gold?

What are the limitations of Rutherford’s model of the atom?

Rutherford’s alpha-particle scattering experiment was responsible for the discovery of ______.

Name the Tissue that forms the inner lining of our mouth.

Identify the type of tissue in the skin.

Identify the type of tissue in the lining of kidney tubule.