Is Matter Around Us Pure? — Science STD 9 — Question

A bulb lights up when connected to a battery. State the energy change which takes place:

1. In the battery.
2. In the bulb.

Which contains more heat, 1kg of water at 100°C or 1kg of steam at 100°C? Give reason for your answer.

Give reason for the following:
The force of gravitation between two cricket balls is extremely small but that between a cricket ball and the earth is extremely large.

The hanging bob of a simple pendulum is displaced to one extreme position B and then released. It swings towards centre position A and then to the other position C. In which position does the bob have:

1. Maximum potential energy?
2. Maximum kinetic energy?

Give reasons for your answer.

How will you test whether a given solution is a colloidal solution?

State whether the following objects possess kinetic energy, potential energy, or both:

1. A man climbing a hill.
2. A flying aeroplane.
3. A bird running on the ground.
4. A ceiling fan in the off position.
5. A stretched spring lying on the ground.

21.5g of sodium chloride dissolves in 60g of water at 25°C. Calculate the solubility of sodium chloride at that temperature.

Explain why, the motion of a body which is moving with constant speed in a circular path is said to be accelerated.

A tortoise moves a distance of 100 metres in 15 minutes. What is the average speed of tortoise in km/h?