ChemistryCLASS 10CBSE
answered 28 May 2026What is meant by a substance in chemistry?
A.VERIFIED ANSWERfact-checked by tutors
A pure substance has a definite and uniform chemical composition and cannot be separated into simpler components by physical methods.
Two types:
- Elements one kind of atom (e.g., gold, oxygen)
- Compounds two or more elements in fixed ratio (e.g., water, salt)
| Pure Substance | Mixture |
|---|---|
| Fixed composition | Variable composition |
| Specific melting/boiling point | Range of values |
| Examples: H₂O, NaCl, O₂ | Examples: Air, seawater, soil |
A pure substance has a uniform, fixed chemical composition and cannot be separated by physical means it is either an element or a compound.