Give three features of cardiac muscles.

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?

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?

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

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?

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

Name the technique to separate

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

How are simple tissues different from complex tissues in plants?

Explain how sound is produced by your school bell.

How does the atmosphere act as a blanket?

Flash and thunder are produced simultaneously. But thunder is heard a few seconds after the flash is seen, why?

Under which of the following conditions is a person most likely to fall sick?
(a) when she is recovering from malaria.
(b) when she has recovered from malaria and is taking care of someone suffering from chicken-pox.
(c) when she is on a four-day fast after recovering from malaria and is taking care of someone suffering from chicken-pox. Why?

Under which of the following conditions are you most likely to fall sick?
(a) when you are taking examinations.
(b) when you have travelled by bus and train for two days.
(c) when your friend is suffering from measles.

Why?

Name A,B,C,D,E and F in the following diagram showing change in its state

Fill in the gaps in the following table illustrating differences between prokaryotic and eukaryotic cells.

Find the energy in kW h consumed in 10 hours by four devices of power 500 W each.

In each of the following a force, F is acting on an object of mass, m. The direction of displacement is from west to east shown by the longer arrow. Observe the diagrams carefully and state whether the work done by the force is negative, positive or zero.