7
Question Question 7
Why is ice at 273 K more effective in cooling than water at the same temperature?
The latent heat of fusion of ice is 336 J g-1 so it absorbs 336 J of heat and changes to water at 0°C and then water at 0°C absorbs heat and temperature is raised. Therefore, ice at 0°C absorbs extra heat in comparison to water at 0°C (due to latent heat of fusion). Hence, ice at 0°C has greater cooling effect than water at 0°C.
BRIGHT TUTORIALS
BRIGHT TUTORIALS
CBSE Class IX | Academic Year 2026-2027
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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