Download Solutions of all the Chapters of Class 9 Science<\/strong>: <\/p>\n\n\n\n Here are NCERT Solutions of Class 9 Science Chapter 1 \u2018Matter in Our Surroundings\u2019 to the questions in the exercise section of the lesson. <\/p>\n\n\n\n 1. Convert the following temperature to Celsius scale.<\/strong><\/p>\n\n\n\n (a) 293K (b) 470K<\/strong><\/p>\n\n\n\n Solution<\/strong>:<\/p>\n\n\n\n 0\u00b0C=273K<\/p>\n\n\n\n (a) 293K= (293 \u2013 273)\u00b0C = 20\u00b0C<\/p>\n\n\n\n (b) 470K= (470 \u2013 273)\u00b0C = 197\u00b0C<\/p>\n\n\n\n 2.Convert the following temperatures to the Kelvin scale.<\/strong><\/p>\n\n\n\n (a) 25\u00b0C (b) 373\u00b0C<\/strong><\/p>\n\n\n\n Solution<\/strong>:<\/p>\n\n\n\n 0\u00b0C = 273K<\/p>\n\n\n\n (a) 25\u00b0C = (25+273)K = 298K<\/p>\n\n\n\n (b) 373\u00b0C = (373+273)K = 646K<\/p>\n\n\n\n 3. Give reason for the following observations: <\/strong><\/p>\n\n\n\n (a) Naphthalene balls disappear with time without leaving any solid.<\/strong><\/p>\n\n\n\n (b) We can get the smell of perfume while sitting several metres away.<\/strong><\/p>\n\n\n\n Solution<\/strong>:<\/p>\n\n\n\n (a) Naphthalene balls, at room temperature, directly go from solid state to gaseous state without changing to liquid state. This is known as sublimation. Hence, they disappear with time without leaving any solid. <\/p>\n\n\n\n (b) Perfumes are volatile substances which means they change from liquid to gas at room temperature. And gas particles have high kinetic energy, so they spread fast. Hence, even while sitting several meters away, we are able to smell the perfume. <\/p>\n\n\n\n 4. Arrange the following in increasing order of forces of attraction between the particles \u2013 water, sugar, oxygen.<\/strong><\/p>\n\n\n\n Solution<\/strong>:<\/p>\n\n\n\n Oxygen (gas) < water (liquid) < sugar (solid)<\/p>\n\n\n\n 5. What is the physical state of water at \u2013 <\/strong><\/p>\n\n\n\n (a) 25\u00b0C (b) 0\u00b0C (c) 100\u00b0C?<\/strong><\/p>\n\n\n\n Solution<\/strong>:<\/p>\n\n\n\n (a) At 25\u00b0C, the water will be liquid at normal room temperature. <\/p>\n\n\n\n (b) 0\u00b0C is the freezing point of water, hence, solid and liquid, both forms will be observed. <\/p>\n\n\n\n (c) 100\u00b0C is the boiling point of water, hence liquid and gaseous, both forms of water will be observed. <\/p>\n\n\n\n 6. Give two reasons to justify \u2013<\/strong><\/p>\n\n\n\n (a) Water at room temperature is a liquid.<\/strong><\/p>\n\n\n\n (b) An iron almirah is a solid at room temperature.<\/strong><\/p>\n\n\n\n Solution<\/strong>:<\/p>\n\n\n\n (a) The boiling point of water is 100 degrees Celcius which is much more than the normal room temperature. Hence, at room temperature, water exists as a liquid. <\/p>\n\n\n\n (b) The melting point of metals is much higher than the room temperature. Hence, an iron almirah is solid at room temperature. <\/p>\n\n\n\n 7. Why is ice at 273K more effective in cooling than water at the same temperature?<\/strong><\/p>\n\n\n\n Solution<\/strong>: At 273 Kelvin, ice will absorb the latent heat to overcome the forces of attraction of the molecules and will turn to water still retaining the same temperature, but water at the same temperature will not absorb excess latent heat from the surroundings. Hence, at 273 Kelvin, ice is more effective in cooling than water. <\/p>\n\n\n\n 8. What produces more severe burns, boiling water or steam?<\/strong><\/p>\n\n\n\n Solution<\/strong>: Steam will cause more severe burns compared to boiling water because steam will first release the heat that had been consumed during the vaporization while still maintaining the same temperature. <\/p>\n\n\n\n 9. Name A, B, C, D, E and F in the following diagram showing a change in its state.<\/strong><\/p>\n\n\n\n Solution<\/strong>: <\/p>\n\n\n\n Credits: NCERT<\/p>\n\n\n\n (A) Solid to Liquid -> Melting (or) fusion (or) liquefaction<\/p>\n\n\n\n (B) Liquid to Gas -> Evaporation (or) vaporization<\/p>\n\n\n\n (C) Gas to liquid -> Condensation<\/p>\n\n\n\n (D) Liquid to Solid -> Solidification<\/p>\n\n\n\n (E) Solid to Gas -> Sublimation<\/p>\n\n\n\n (F) Gas to Solid -> solidification <\/p>\n\n\n\n Download the NCERT Solutions of Class 9 Science Chapter 1 PDF Here! <\/strong><\/a><\/p>\n\n\n\n Download Solutions of all the Chapters of Class 9 Science<\/strong>: <\/p>\n\n\n\nChapter 1<\/td> Chapter 2<\/strong><\/td> Chapter 3<\/strong><\/td> Chapter 4<\/strong><\/td> Chapter 5<\/strong><\/td> Chapter 6<\/strong><\/td><\/tr> Chapter 7<\/strong><\/td> Chapter 8<\/strong><\/td> Chapter 9<\/strong><\/td> Chapter 10<\/strong><\/td> Chapter 11<\/strong><\/td> Chapter 12<\/strong><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n NCERT Solutions Class 9 Science Chapter 1 Matter in Our Surroundings <\/h2>\n\n\n\n
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