Question 1.Which of the following are matter? Chair, air, love, smell, hate, almonds, thought, cold, cold drink, smell of perfume.
Answer: Chair, Sir, smell, almonds, cold drink and smell of perfume.
Question 2.Give reasons for the following observation: The smell of hot sizzling food reaches you several metres away, but to get the smell from cold food, you have to go close.
Answer: This happens because rate of diffusion of gas increases with increase in temperature. In case of hot food, diffusion of smell is faster whereas in case of cold food, diffusion is slower.
Question 3. A diver is able to cut through water in a swimming pool. Which property of matter does this observation show?
Answer: The particles of water are held together by forces of attraction. As these forces are not strong, the diver is able to cut through water in a swimming pool. This observation shows that particles of matter attract one another.
Question 4. What are the characteristics of the particles of matter?
Answer: The characteristics of the particles of matter are as follows :
(a) Matter consists of tiny particles which cannot be seen by an individual with naked eye.
(b) The particles of matter have spaces between them.
(c) The particles of matter attract each other due to inter molecular forces of attraction. The forces of attraction are maximum in solids and minimum in gases. Liquids have inter molecular forces in between solids and gases.
(d) The particles of matter are not stationary but are continuously moving.
(e) The inter molecular forces decrease with the increase in inter molecular spaces and vice-versa.
(f) Kinetic energy of the molecules increases with the rise in temperature.
Question 5.The mass per unit volume of a substance is called density, (density = mass/volume) Arrange the following in order of increasing density – air, exhaust from chimneys, honey, water, chalk, cotton and iron.
Answer:The increasing order of density is air < exhaust from chimney < cotton < water < honey < chalk < iron.
