Question

Choose the correct statement from the following:
A. Molecular collisions are unaffected by gravity.
B. Real gases obey gas laws under any conditions.
C. Gas laws have no significance at absolute zero.
D. At ${0^ \circ }C$, the molecular motion ceases.

Answer 1

Hint: In order to react, the two molecules A and B must come into contact with sufficient force so that chemical bonds break. Such an encounter is called a collision.
The gas laws are a group of laws that depict the behaviour of gases by providing relationships between many characteristics of gases.
Absolute zero is the lowest temperature possible where nothing can be colder and there is no heat energy left in a substance.
The temperature at which the molecular motion ceases, was determined by Charles law.

Complete step by step answer:
Option A says that there’s no effect of gravity on molecular collisions. It is a known fact that gravitational force is everywhere on the planet. The collision of the gases taking place creates force that overtakes the gravitational attraction. Thus gravity has no effect on the collisions of molecules.
Option B says real gases obey the gas laws under any conditions. The statement is incorrect. An ideal gas obeys laws under all conditions of temperature and pressure. Real gases obey gas laws only when the pressure is very low and the temperature is very high.
Option C says at absolute zero there’s no significance of gas laws. The hypothetical temperature is $ - {273^ \circ }C$ at which volume of any gas becomes zero is referred to as absolute zero. So, there is no significance of gas laws at absolute zero.
Option D says at ${0^ \circ }C$, the motion of molecules ceases. Actually, the motion of molecules at $0K$ not at ${0^ \circ }C$.
Charles law states that molecular motion at $0K$ or $ - {273^ \circ }C$ (absolute zero)

So, the correct answer is Option A,C.

Note: Gas molecules are found in an area in which gravity is present.
The force exerted among the gases by the collisions effectively revamps the force of gravity.
Every real gas condenses to a liquid or a solid at any temperature higher than absolute zero. So gases do not obey gas laws at absolute zero.