Chapter 1
Matter in Our Surroundings
Q1. Which of the following are matter?
Chair, air, love, smell, hate, almonds, thought, cold, cold-drink, smell of perfume.
Answer: Chair, air, almonds, cold drink and smell of perfume.
Q2. 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.
Answer: We know that, with an increase in temperature of a substance the kinetic energy of a substance increases, and hence rate of diffusion of gas increases .
Thus, the smell of hot sizzling food reaches you several meters away, but to get the smell from cold food you have to go close.
Q 3. A diver is able to cut through water in a swimming pool. Which property of matter does this observation show?
Answer: This shows that the particles of water have intermolecular space between them .
Q 4. What are the characteristics of the particles of matter?
Answer. The characteristics of the particles of matter are:
(1) Particles have inter-molecular space.
(2) Particles have inter-molecular force.
(3) Particles of matter are moving continuously.
Q 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: Increasing density:
air < exhaust from chimneys < cotton < water < honey < chalk < iron.
Question 2. (a) Tabulate the differences in the characteristics of states of matter.
(b) Comment upon the following: rigidity, compressibility, fluidity, filling a gas container, shape, kinetic energy and density.
Answer: (a) Difference in the characteristics of 3 states of matter.
