Question

The metal which has low melting point is:
A.$Mg$
B.$K$
C.$Cu$
D.$Fe$

Answer 1

Metals are shiny in nature, malleable, ductile, have high melting and boiling points, react with oxygen and so many others while non-metals are not shiny, non-malleable, non-ductile, have low melting and boiling points, generally do not react with oxygen or air, generally blurred to see.

Complete step by step solution:
First of all we will talk about metals, non-metals and their properties.
Elements: A substance which cannot be broken down further by chemical and physical method, is called an element. They are made up of atoms. All the atoms in an element are of the same kind.
Elements are classified into two categories:
Metals and Non-metals
Physical properties of metals and non-metals
Metals: Metals are solid at room temperature except mercury which is liquid at room temperature. They are shiny in nature. The property of shiny nature is known as metallic lustre. They are silvery-grey in colour. They are hard to cut but sodium and potassium are soft as they can cut by knife. They are malleable (which can be drawn into thin sheets). they are ductile (which can be drawn into wires). They are good conductors of heat and electricity (they allow heat and electricity to pass through them). They can bear high tensile strength. They have high densities. They have high melting and boiling points except sodium and potassium. They are sonorous in nature (which produce sound when struck hard).
Non-Metals: Non-Metals may be solid, liquid or gas at room temperature. They are not shiny in nature. The property of shiny nature is known as metallic lustre. So they are not lustrous in nature. They are different in colour. For example: sulphur is yellow, phosphorus is white or red. They are soft except diamond which is the hardest substance on the earth. They are non-malleable (which can not be drawn into thin sheets). They are non-ductile (which can not be drawn into wires). They are bad conductors of heat and electricity (they do not allow heat and electricity to pass through them). They can not bear high tensile strength. They have low densities. They have low melting and boiling points. They are non-sonorous in nature (which do not produce sound when struck hard).
So the metal which has a low melting point is potassium $K$.

So, option B is the correct answer.

Note: There are so many exceptions for the physical properties of metals and non-metals. For example: generally metals are hard to cut but sodium and potassium are very soft that they can be cut by knife. Generally non-metals are light but diamond is the hardest substance which is known to us.