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Question Question 1
Why does a desert cooler cool better on a hot dry day?
A dessert cooler works on the principle of evaporation. In hot and dry conditions, the air has low humidity, which means it can absorb more water vapour leading to more efficient evaporation and, consequently, better cooling effects compared to a humid day.
BRIGHT TUTORIALS
BRIGHT TUTORIALS
CBSE Class IX | Academic Year 2026-2027
9403781999
Excellence in Education
Science | Chapter 1: Matter in Our SurroundingsWeb Content — Quick Reference
Chapter 1: Matter in Our Surroundings — Quick Reference
Quick Revision Points
- Matter has mass and occupies space; made of particles with spaces, motion, and attraction
- Three states: Solid (fixed shape/volume), Liquid (fixed volume, not shape), Gas (neither fixed)
- Melting point of ice = 0°C (273 K); Boiling point of water = 100°C (373 K)
- Latent heat of fusion of ice = 334 J/g; Latent heat of vaporisation of water = 2260 J/g
- Sublimation: solid → gas directly (camphor, dry ice, naphthalene)
- Evaporation: surface phenomenon at all temperatures; causes cooling; factors: surface area, temperature, humidity, wind
- Temperature conversion: T(K) = T(°C) + 273
Exam Tips for Chapter 1
- 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: ch01-matter-in-our-surroundings.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