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

Convert into mole.

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

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?

Why is the atmosphere essential for life?

Why is the weight of an object on the moon 1/6th its weight on the earth?

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?

Soni says that the acceleration in an object could be zero even when several forces are acting on it. Do you agree with her? Why?

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?

List any three human activities that you think would lead to air pollution.

Explain the working and application of a sonar.

How are pteridophytes different from the phanerogams?

What is a tissue?

What are the functions of the stomata?

What is the role of epidermis in plants?

How does the cork act as a protective tissue?

Name the regions in which parenchyma tissue is present.

Two objects, each of mass 1.5 kg, are moving in the same straight line but in opposite directions. The velocity of each object is 2.5 m s^-1 before the collision during which they stick together. What will be the velocity of the combined object after collision?

Name types of simple tissues.

If bromine atom is available in the form of, say, two isotopes ⁷⁹₃₅ Br (49.7%) and ⁸¹₃₅ Br (50.3%), calculate the average atomic mass of bromine atom.

Convert into mole.

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