Introduction:
A substance can indeed exist in a pure form of matter. Pure substances are materials that consist of only one type of element or compound, without any impurities or mixtures. These substances have a uniform composition and distinct properties, making them different from mixtures.

Definition of a Pure Substance:
A pure substance is a material that contains only one type of particle, either atoms or molecules, and has a fixed or definite composition. It cannot be broken down into simpler components through physical methods.

Example of a Pure Substance:
One suitable example of a pure substance is water (H₂O). Water is composed of hydrogen and oxygen atoms, bonded together in a fixed ratio of 2:1. It exists in three different physical states: solid (ice), liquid (water), and gas (water vapor), each with its own characteristic properties.

Properties of Pure Water:
Pure water has several distinct properties that make it a pure substance:
1. Homogeneous Composition: Pure water has a uniform composition throughout its sample, meaning that it contains the same ratio of hydrogen and oxygen atoms in every part.
2. Fixed Composition: The ratio of hydrogen to oxygen atoms in water is always 2:1, regardless of the quantity or source of the water.
3. Boiling and Melting Points: Pure water has specific boiling and melting points, which are 100°C and 0°C, respectively, at standard atmospheric pressure.
4. Density: Pure water has a density of 1 gram per cubic centimeter (g/cm³) at 4°C, which is a characteristic property of the substance.
5. Chemical Stability: Water does not decompose into simpler substances under normal conditions, which further supports its purity.

Impurities in Water:
Although water can exist as a pure substance, it is crucial to note that natural water sources often contain impurities. These impurities can include dissolved minerals, gases, organic matter, and microorganisms. However, through various purification processes such as distillation or reverse osmosis, these impurities can be removed, resulting in the production of pure water.

Conclusion:
In conclusion, a substance can exist in a pure form of matter. Pure substances have a uniform composition and distinct properties, making them different from mixtures. Water is a suitable example of a pure substance, as it consists of hydrogen and oxygen atoms bonded in a fixed ratio. However, it is essential to acknowledge that naturally occurring water sources often contain impurities, which can be removed through purification processes to obtain pure water.

Elements are said to be the purest form of substance