Matter In Our Surroundings Subjective Type

(a) Define the term diffusion.

(b) Why do the liquids have a higher rate of diffusion than solids?

(c) What change occurs to the water when wet clothes dry up?

Give reasons for the following:

(a) A gas fills completely the vessel in which it is kept.

(b) A gas exerts more pressure on the walls of the container than solids.

(c) A wooden table should be called a solid.

(a) When common salt is added to water, it dissolves. Explain.

(b) The melting points of solid (A), (B), (C) and (D) are 50°C, 250°C, 110°C, and 160°C respectively.  Name the solid which has the strongest inter-particle forces of attraction.

(c)Suppose you are going out on a hot summer day. Should you wear a cotton T-shirt or a nylon T-shirt? Give reason also.

(d)Which is more volatile: – Liquid A (Boiling point 85 °C) or water (Boiling point 100°C)?

Answer the following:

(a) Define fusion.

(b) Give the names of two substances that undergo sublimation.

(c) Why do solids not diffuse?

(a) What do you understand by the term dry ice?

(b) What is the physical state of water at

1. i) 250◦C           (ii) 100◦C

(a) If we break a piece of chalk, a wooden block, and an iron nail, we will observe that it is very difficult to break an iron nail, wooden blocks require lesser force while chalk can be broken easily. What can be concluded from these observations?

(b)Though sponges can be compressed yet they are considered solid. Give reasons.

(a)Which out of wood, sugar, water, and hydrogen will exert the highest pressure on the walls of the container?

(b)Freezing point of water is 0°C, what will be its melting point?

(c)What do you understand by liquefaction?

(d)Why do clothes dry up quickly on a windy day?

(a)Why is it possible to compress oxygen?

(b)Why do gases have fluidity?

(c)Density of gases is low. Give reason.

(d)You have copper, water, and oxygen. Which will have the highest density and why?

(e)Name two fuels that are based on the property of compressibility of gases?