Convert the following temperature to celsius scale:

a. 300 K              b. 573 K.

Convert into mole.

(a) 12 g of oxygen gas
(b) 20 g of water
(c) 22 g of carbon dioxide.

Why is the atmosphere essential for life?

You find your mass to be 42 kg on a weighing machine. Is your mass more or less than 42 kg?

What happens to the force between two objects, if
(i) the mass of one object is doubled?
(ii) the distance between the objects is doubled and tripled?
(iii) the masses of both objects are doubled?

Why are we normally advised to take bland and nourishing food when we are sick?

Illustrate the law of conservation of energy by discussing the energy changes which occur when we draw a pendulum bob to one side and allow it to oscillate. Why does the bob eventually come to rest? What happens to its energy eventually? Is it a violation of the law of conservation of energy?

In which of the following case do you think the long-term effects on your health are likely to be most unpleasant?
  •  if you get jaundice,
  •  if you get lice,
  •  if you get acne.

Why?

Name the technique to separate

(i) butter from curd,
(ii) salt from sea-water,
(iii) camphor from salt.

What are the immunisation programmes available at the nearest health centre in your locality? Which of these diseases are the major health problems in your area?

A stone is released from the top of a tower of height 19.6 m. Calculate its final velocity.

Draw a sketch of Bohr’s model of an atom with three shells.

Calculate the molecular masses of H₂, O₂, Cl₂, CO₂, CH₄, C₂H₆, C₂H₄, NH₃, CH₃OH.

Can there be displacement of an object in the absence of any force acting on it? Think. Discuss this question with your friends and teacher.

A person holds a bundle of hay over his head for 30 minutes and gets tired. Has he done some work or not? Justify your answer.

Write a note on how forests influence the quality of our air, soil and water resources.

A stone is released from the top of a tower of height 19.6 m. Calculate its final velocity.

You find your mass to be 42 kg on a weighing machine. Is your mass more or less than 42 kg?

A trolley, while going down an inclined plane, has an acceleration of 2 cm s^-2. What will be its velocity 3 s after the start?

How is our atmosphere different from the atmospheres on Venus and Mars?

What is the importance of universal law of gravitation?