Question

The melting point of a substance is $97.9^\circ C$ at atmospheric pressure. At room temperature , the state of the substance is
A.Solid
B.Liquid
C.Gas
D.Plasma

Answer 1

The substance’s melting point and boiling point with respect to room temperature at atmospheric pressure determines whether the substance is liquid, gas or solid at room temperature. $97.9^\circ C$ is much greater than the normal room temperature.

Complete step by step answer:
A state of substance at normal conditions can be determined by looking into its melting or boiling point.
We know that the normal room temperature is between $20^\circ C - 25^\circ C$. Here the given melting point of the substance is $97.9^\circ C$, that is much more than that of normal room temperature. So in room temperature at atmospheric pressure the substance has not melted yet. This clearly says that the substance is in solid state.
So the correct answer is option A solid.

Additional information:
For a solid substance at room temperature and atmospheric pressure, its melting point should be greater than that of the room temperature.
If a substance is liquid at room temperature, then the melting point will be less than that of room temperature which means it is already in a melted state.
For a gas to exist in room temperature its boiling point should be less than that of room temperature so that it's already in a boiled state before attaining the room temperature.
Plasma is a state which occurs at a very high temperature where even the electrons get separated from its atom and are free to move.

Note:
If the melting point of a given substance is very high then we can make sure that it is definitely at solid state at normal conditions. That is it is packed in very closely and tightly so that much amount of energy or temperature is needed to escape the molecule from its crystal lattice to change into either liquid or gas.