This set of Class 11 Chemistry Chapter 5 Multiple Choice Questions & Answers (MCQs) focuses on “States of Matter – Kinetic Molecular Theory of Gases”.
1. Which of the following assumption explains great compressibility of gases?
a) the actual volume of the gas molecules is negligible
b) there is no force of attraction
c) particles are always in random motion
d) different particles have different speeds
View Answer
Explanation: Gas molecules are considered as point masses because the actual volume of gas molecules is negligible when compared to the space between them, so this assumption explains the greater compressibility of gases.
2. Gases ________ and occupy all the space that is available to them.
a) contract
b) compress
c) expand
d) shrink
View Answer
Explanation: At normal temperature and pressure, there is no force of attraction between the gas particles. So they expand and occupy the space that is available. This statement supports the assumption.
3. Gases do not have a fixed shape.
a) true
b) false
View Answer
Explanation: Particles do not have a fixed shape because they are always in random motion and particles never occupy fixed position the keep on moving and never occupy a particular shape this is the reason to prove that the above statement is true.
4. Why do you think the pressure is exerted by the gas on the walls of the container in all directions?
a) they consist of identical particles
b) collide with each other during random motion
c) lack of definite shape
d) more forces of attraction
View Answer
Explanation: As the particles of gas travel in straight lines and move in a random motion and collide with each other and also collide with the walls of the container, the pressure is exerted on the walls of the container in all directions.
5. Collisions of gas molecules are ___________
a) perfectly elastic
b) inelastic
c) always occur in a proper and predicted motion
d) not conserved
View Answer
Explanation: The total energy of molecules before the collision is equal to the total energy after the collision. That means there may be an exchange of energy between the molecules but the total energy does not change, so the collisions of gas molecules are elastic.
6. At an instance different particles have ________ speeds.
a) same
b) different
c) opposite
d) similar
View Answer
Explanation: According to the kinetic molecular theory of gases, the assumption that different particles have different speeds at a time is because particles do not always have the same speeds and move in different directions but we can assume that the distribution of speeds is constant at a particular temperature.
7. There is an increase in temperature of an object then the kinetic energy of the object __________
a) decreases
b) increases
c) remains the same
d) it is not related to the temperature
View Answer
Explanation: From the kinetic molecular theory of gases we can know that the kinetic energy of an object is proportional directly to the Absolute Temperature of that object so when the temperature of an object increases obviously the kinetic energy also increases.
8. The temperature of a gas is 100 K it is heated until it is 200 k then, what do you understand regarding kinetic energy in this process?
a) halved
b) tripled
c) quadrupled
d) doubled
View Answer
Explanation: According to the kinetic molecular theory of gases, if the Absolute Temperature of a gas is doubled then the kinetic energy is also doubled because they are directly proportional to each other so here the answer is doubled. If the temperature doubles from 100 k to 200 k, kinetic energy also doubles.
9. Which of the following is not a postulate of Kinetic molecular theory of gases?
a) the actual volume of gas molecules is negligible
b) there are high forces of attraction between the gas molecules
c) collisions are elastic in gas molecules
d) kinetic energy of gas molecules is directly proportional to the absolute temperature
View Answer
Explanation: According to Kinetic molecular theory of gases, there are no forces of attraction between the particles of gas at normal temperature and pressure. This is because gases expand and occupy all the space available.
10. Which of the following statements do you think is the correct one?
a) in gases there is a predominance of intermolecular energy
b) all molecules have the same speed at different temperatures
c) collisions of gas molecules are elastic
d) do not exert the same pressure in all directions
View Answer
Explanation: Collisions are elastic as the total amount of energy before and after the collision is the same. The correct statements of the incorrect ones are: in gases, there is a predominance of thermal energy, the distribution of speeds remains constant at a particular temperature and the gases exert the same pressure in all directions of the container.
Sanfoundry Global Education & Learning Series – Chemistry – Class 11.
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