(Worksheet - Questions asked in CBSE Papers)
Very short Answer Questions (1 mark)
1. What is common among the three states of matter?
2. Which property of gas is used in supplying oxygen cylinders to hospitals?
3. What is dry ice ? What happens when the pressure under which it is stored is decreased to 1 atmosphere ?
4. Why does the smell of hot cooked food reach you several metres away within second.
5. Why evaporation is called surface phenomenon?
6. At what temperature does solid ice and liquid water co-exist together?
7. Arrange the three states of matter in increasing order of their compressibility.
Short Answer Questions (2 marks)
8. The following triangle exhibits interconversion of the three states of matter. Complete the triangle by labelling the arrows marked A, B, C and D.
9. Why should we wear cotton clothes during summer?
10. Convert the following temperatures to
(a) Celsius scale (i) 313 K (ii) 370 K
(b) Kelvin scale (i) 23° C (ii) 73° C
11. Why does a desert cooler cool better on a hot dry day?
12. What will happen when we start putting pressure and compress a gas enclosed in a cylinder? Do you think that increasing or decreasing the pressure and temperature can change the state of matter. Justify your answer with an example.
Short Answer Questions (3 marks)
13. Define the following terms.
(a) Latent heat of fusion.
(b) Melting point.
14. Give reasons for the following :
(a) Why does Ice float on water ?
(b) Why does a gas fill completely the vessel in which it is kept ?
(c) Latent heat of evaporation of two liquids A and B is 100 J/kg and 150 J/kg respectively. Which one can produce more cooling effect and why ?
15. Give reasons for the following:
(a) A sponge is a solid but can be easily compressed.
(b) Clothes dry faster on a windy day.
(c) Smell of perfume travels a few yards away.
16. (a) What happens when acetone is poured on the palm?
(b) Name the process involved in the following changes:
17. What determine the state of a substance ? Suggest a method to liquefy gases. Water droplets are observed on the outer surface of a glass tumbler containing ice cold water. Give reason.
18. Give reason :
(a) Steam produces more severe burns as compared to boiling water.
(b) Temperature of a liquid does not change when it boils.
19. (a) Define evaporation
(b) Explain how the following factors affect the rate of evaporation of a liquid:
(i) temperature of the liquid.
(ii) area of the exposed surface.
(iii) moisture in the surrounding air.
(iv) increase in wind speed.
20. With the help of a labelled diagram describe a activity to show that nature of matter is particulate and not continuous.
Use the following material : beakers/glass, spoon, glass rod and sugar.
Long Answer Questions (5 Marks)
21. Compare in tabular form properties of solids, liquids and gases with respect to :
(v) Fluidity or Rigidity
22. (a) Define matter. Name the state of matter in which the forces between the constituent particles are: (i) Strongest, (ii) Weakest.
(b) Give reasons for the following :
(i) A liquid generally flows easily.
(ii) Ice at 0°C appears colder to the mouth than water at 0°C. Why ?
(iii) Doctors advise to put strips of wet cloth on the forehead of a person having high temperature.
23. (i) What is meant by evaporation of a liquid ? Water kept in an earthen pot becomes cool during summer. Why ?
(ii) With the help of a labelled diagram, describe in brief an activity to show sublimation of ammonium chloride.