2. A sponge can be pressed easily, still it is called a solid. Why?
3. Differentiate solids liquids and gases on the basis of (a) diffusion , (b) density.
4. Solids are denser as compared to liquids , still ice floats on water. Explain.
5. Define Latent heat of fusion.
6. Why does water vapour has more energy than water at same temperature?
7. How can gases be liquefied?
8. List four factors which affect the rate of evaporation.
9. Name and define the fourth and fifth state of matter.
10. Why does a desert cooler cool better on a hot, dry day?
11. Why does temperature remain constant during the boiling of water even though heat is supplied continuously?
12. What is the chemical name of Dry Ice? Why is it called dry ice?
13. What are alloys? Is it a mixture or a compound? Give reasons.
14. List four reasons to support that water is a compound and not a mixture.
15. Distinguish between homogeneous and heterogeneous mixture. Classify the following mixtures as homogeneous or heterogeneous-
i) Tincture of iodine
ii) Smoke
iii) Brass
iv) Sugar solution
16. Distinguish between true solution, suspension and colloid on the basis of stability, filterability and type of mixture.
17. How will you prepare a 10% solution of glucose in water?
18. Identify the physical and chemical changes from the following:-
i) Burning of magnesium in air
ii) Tarnishing of silver spoon
iii) Sublimation of iodine
iv) Electrolysis of water
19. State one similarity and one difference between evaporation and boiling.
Fill in the blanks:-
1. Particles of matter are continuously moving, so they possess ____________________.
2. The melting point of ice is __________________.
3. 293 K = ____________° C.
4. The concentration of a solution is the amount of _______________ present in a given volume of solution.
5. _______________ is the only metal which is liquid at room temp.
6. ________________ mixtures have uniform composition.
7. S.I. unit of latent heat of melting is ______________.
8. Rate of evaporation __________________ when surface area of liquid is increased.
9. Particles of matter have ______________ between them.
10. Soil and minerals are not ____________substances.
11. __________ number of elements occur in nature.
12. _________________ is a non-metal which is liquid at room temperature.
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