7
Question Question 7
Which of the following materials fall into the category of 'pure substance'?
(a) Ice
(b) Milk
(c) Iron
(d) Hydrochloric acid
(e) Calcium oxide
(f) Mercury
(g) Brick
(e) Wood
(f) Air
Following substances from the above-mentioned list are pure substances:
Ice
Iron
Hydrochloric acid
Calcium oxide
Mercury
BRIGHT TUTORIALS
BRIGHT TUTORIALS
CBSE Class IX | Academic Year 2026-2027
9403781999
Excellence in Education
Science | Chapter 2: Is Matter Around Us PureWeb Content — Quick Reference
Chapter 2: Is Matter Around Us Pure — Quick Reference
Quick Revision Points
- Pure substances: fixed composition (elements + compounds). Mixtures: variable composition
- Solution (< 1 nm, transparent), Colloid (1-100 nm, Tyndall effect), Suspension (> 100 nm, settles)
- Concentration = (mass of solute / mass of solution) × 100
- Separation: evaporation, centrifugation, chromatography, distillation, sublimation, crystallisation, separating funnel
- Elements: metals, non-metals, metalloids. Compounds: fixed ratio, chemical separation
- Tyndall effect: scattering of light by colloidal particles (milk, fog, smoke)
Exam Tips for Chapter 2
- Read the detailed chapter notes for complete coverage of all NCERT topics.
- Practice all NCERT in-text and back exercise questions — they are frequently asked in exams.
- Focus on comparison tables, diagrams, and definitions — these are high-scoring areas.
- For numericals (if applicable), practice at least 20 problems of varying difficulty.
- Refer to the practice question bank (200+ questions) for thorough preparation.
Related Resources
- Detailed Notes: ch02-is-matter-around-us-pure.html
- Practice Questions: 100+ questions with answers in 05-practice-questions/
- Chapter Test: 30-mark test paper in 06-tests/chapter-tests-30marks/
- Formula Sheet: Complete formula reference in 03-teacher-aid/formula-sheet.html