Important questions based on NCERT syllabus for Chapter 5 - States of Matter:
Question-1: Critical temperature for CO2 and CH4 are 31.1°C and -81.9°C respectively. Which of these has stronger intermolecular forces and why ?
Solution: Higher the critical temperature, more easily the gas can be liquefied, i.e., greater are the intermolecular forces of attraction. Hence, CO2 has stronger intermolecular forces than CH4.
Question-2: Name four properties of gases.
Solution: Gases, have no definite shape and no definite volume.
There is no force of attraction existing between the molecules of gases.
Gases are highly compressible.
Gases’can mix evenly and can spread in whole space.
Question-3: (a) What do you mean by’Surface Tension’of a liquid?
(b) Explain the factors which can affect the surface tension of a liquid.
Solution: (a) Surface tension: It is defined as the force acting per unit length perpendicular to the line drawn on the surface. It’s unit is Nnr1.
(b)Surface tension of a liquid depends upon following factors.
(i)Temperature: Surface tension decreases with rise in temperature. As the temperature of the liquid increases, the average kinetic energy of the molecules increases. Thus, there is a decrease in intermolecular force of attraction which decreases the surface tension.
(ii)Nature of the liquid: Greater the magnitude of intermolecular forces of attraction in the liquid, greater will be the value of surface tension.