Question

Pure substances have a fixed ……. and ……. set of properties.

• A. composition
• B. definite

Answer 1

• Pure substances are classified into two categories elements and compounds.
• A pure substance, such as salt or sugar, has a defined and consistent composition.
• A pure material is either an element ( or a compound), but its composition remains consistent.
• For example, In water hydrogen(H) and oxygen(O) are in fixed composition 2:1.
• Pure substance characteristics or properties that remain constant all throughout the sample (e.g., melting point, color, boiling point, etc.).
• For example, The boiling point of water from any source is always equal to $100°C$.

Thus Pure substances have a fixed composition and definite set of properties.