MP Board · Class 9 · Science · Is Matter Around Us PureDefine a pure substance in chemistry. How does it differ from a mixture?

In chemistry, a pure substance consists of a single type of particles, meaning all constituent particles of that substance are identical in their chemical nature (e.g., pure water, sodium chloride). A mixture, on the other hand, contains more than one substance or pure form of matter mixed together in any proportion (e.g., seawater, air). Pure substances have fixed physical properties like melting point and boiling point, whereas mixtures show variable properties depending on their composition.