Wednesday 30 August 2017

CLASS-9
CHEMISTRY WORKSHEET

1.       The rate of evaporation decreases with                                                                                              1M
a.       (a) increase in humidity             (b) increase of temperature
b.      (c) increase in wind speed         (d) increase of surface area
2.       Arrange the following substances in increasing order of force of attraction between the particles.
a.       (i) milk         (ii) salt              (iii) oxygen                                                                                                                     1M
(a)    Conversion of solid into vapours without passing through the liquid state is called vaporization.
(b)   Conversion of vapours into solid without passing through the liquid state is called sublimation.
(c)    Conversion of vapours into solid without passing through the liquid state is called freezing.
(d)   Conversion of solid into liquid is called sublimation.                                                                                                                                                                                                                1M
4.       What is the value of boiling point of water on Kelvin scale of temperature?                                 1M
5.       On converting 25°C, 38°C and 66°C to kelvin scale, the correct sequence of temperature will be:
a.       298 K, 311 K and 339 K
b.      298 K, 300 K and 338 K
c.       273 K, 278 K and 543 K
d.      298 K, 310 K and 338 K                                                                                                                                                                                                     1M
6.       Convert:  
               (a) 27°C into kelvin scale                    (b) 500 K into Celsius scale                                                                                                                                                                                                    2M
7.        What is dry ice? Dry ice is compressed at high pressure. What happens when pressure is released?                                                                                                                                                                                                                                                                                2M
8.       Answer the following questions:
(a)    Why is ice at 273 K more effective in cooling than water at the same temperature?
(b)    Name the two gases which are supplied in compressed form in homes and hospitals.                                                                                                                                                                                                                                                                                             2M                                                          
9.        When a bottle of scent is opened in one corner of a room, it immediately spreads throughout the room. What property of matter is responsible for this observation? Explain                                                                                                                                                        3M
10.    Define (i) Latent heat of fusion and
                           (ii) Latent heat of vaporization.
                           (iii) Give suitable examples for (i) & (ii)                                                                                                                                                                                                                   3M
11.   What is Evaporation? Explain how the following factors affect the rate of evaporation of a liquid:
                                I.            Temperature of the liquid.                                                                                    3M
                              II.            Area of the exposed surface.
                            III.            Moisture in the surrounding air.
                            IV.            Increase in wind speed.                                                                                                                     


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