Question

Q 1 Give reasons for the following observation:
The smell of hot sizzling food reaches you several meters away, but to get the smell from cold

food you have to go close.
Q2 A diver is able to cut through water in a swimming pool. Which property of matter does this observation show?
Q 3 What are the characteristics of the particles of matter?
Q 4 Answer the following.
a) Tabulate the differences in the characteristics of matter.

b) Comment upon the following: rigidity, compressibility, fluidity, filling a gas container,

shape, kinetic energy and density.
Q 5 Give reasons
a) A gas fills completely the vessel in which it is kept.

b) A gas exerts pressure on the walls of the container.

c) A wooden table should be called a solid.

d) We can easily move our hand in the air but to do the same through a solid block of wood we need a karate expert.
Q 6 Liquids generally have a lower density than solids. But you must have observed that ice floats on water. Find out why.
Q 7 Convert the following temperature to Celsius scale:
a. 300K b. 573K

Solution:

a. 0°C=273K

300K= (300-273)°C = 27°C

b. 573K= (573-273)°C = 300°C

What is the physical state of water at:
a. 250°C b. 100°C ?
Q 8 For any substance, why does the temperature remain constant during the change of state?
Q 9 Suggest a method to liquefy atmospheric gases.
Q 10 Why does a desert cooler cool better on a hot dry day?
Q 11 How does the water kept in an earthen pot (matka) become cool during summer?
Q 12 Why does our palm feel cold when we put on some acetone or petrol or perfume on it?
Q 13 Why are we able to sip hot tea or milk faster from a saucer rather than a cup?
Q 14 What type of clothes should we wear in summer?
Q 15 Give reason for the following observations:
(a) Naphthalene balls disappear with time without leaving any solid.

(b) We can get the smell of perfume while sitting several metres away.
Q 16 What is the physical state of water at –
(a) 25°C (b) 0°C (c) 100°C?
Q 17 Give two reasons to justify –
(a) Water at room temperature is a liquid.

(b) An iron almirah is a solid at room temperature.
Q 18 Why is ice at 273K more effective in cooling than water at the same temperature?
Q 19 What produces more severe burns, boiling water or steam?
Q 20 Arrange the following in increasing order of forces of attraction between the particles – water, sugar, oxygen.​

Answer 1

Answer:

1. The smell of hot sizzling food reaches us several meteres away due to the diffusion .

2. It shows the property that particles of matter have space between them.

3. The characteristics of particles of matter are :

They have space between them.

They have force of attraction between them.

They continuously move due to kinetic energy.