Two persons manage to push a motorcar of mass 1200 kg at a uniform velocity along a level road. The same motorcar can be pushed by three persons to produce an acceleration of 0.2 m s^-2. With what force does each person push the motorcar? (Assume that all persons push the motorcar with the same muscular effort.)

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?

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?

Name the technique to separate

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

List any three reasons why you would think that you are sick and ought to see a doctor. If only one of these symptoms were present, would you still go to the doctor? Why or why not?

An object experiences a net zero external unbalanced force. Is it possible for the object to be travelling with a non-zero velocity? If yes, state the conditions that must be placed on the magnitude and direction of the velocity. If no, provide a reason.

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

How many types of elements together make up the xylem tissue? Name them.

What are the functions of areolar tissue?

Explain the basis for grouping organisms into five kingdoms.

List any three reasons why you would think that you are sick and ought to see a doctor. If only one of these symptoms were present, would you still go to the doctor? Why or why not?

Explain how animals in Vertebrata are classified into further subgroups.

Calculate the number of aluminium ions present in 0.051 g of aluminium oxide.
(Hint: The mass of an ion is the same as that of an atom of the same element. Atomic mass of Al = 27 u)

An object of mass 40 kg is raised to a height of 5 m above the ground. What is its potential energy? If the object is allowed to fall, find its kinetic energy when it is half-way down.

Why do you fall in the forward direction when a moving bus brakes to a stop and fall backwards when it accelerates from rest?