Pure substances are in appearance

The Pure substances are Homogenous in appearance

A pure substance ( a homogenous mixture ) appears in uniformity. i.e. all sides of a pure substance regardless of the size of the substance will appear in the same color or texture when observed. some examples of pure substances are ; pure water and steel.     while

An Impure substance is a non-homogenous mixture whereby some parts of the substances will appear in different colors or texture when put under observation.

Hence we can conclude that pure substances are Homogenous in appearance.

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a electronegativity decreases beacuse the size of nucleus is bigger.