Question

A gas has definite_________ but no definite ___________ and__________.
A) Mass, volume, shape
B) Shape, mass, volume
C) Volume, density, mass
D) Volume, mass and shape

Answer 1

Hint:. Answer to this question is based on the fact that the gases are having free motion, that is they can move freely in all directions and this concept can lead you to the correct answer.

Complete step by step answer:
We have learnt the lower sections of our classes about the states of matter which are of 3 forms. But, currently scientists consider four states of matter among which one is a man made.
- The three states of matter well known are solids, liquids and gases
- Among these states of matter we are familiar with their definitions as,
Solids are the ones who have rigid structure and which have a definite volume and shape.
Liquids are those which flow in a particular direction and these are having no definite shape and this actually takes the shape of the container.
The third state of matter is that gases are those matters in which the molecules are not held together but they are moving in the random directions. Therefore, these do not have a definite shape.
- Here, solids and liquids have definite shape and mass and similarly even gases have only definite mass because mass of a substance is not dependent on their shape.
- Therefore, gases take the shape of the container and occupy the complete volume of that particular container.
- Thus, the correct answer to this question is that gases have definite mass but no definite volume and shape.
So, the correct answer is “Option A”.

Note: There can be a confusion with the options containing density but note that density changes along with the change in volume even if mass is the same throughout because density is the ratio of mass by volume.