Alka was making tea in a kettle. Suddenly she felt intense heat from the
puff of steam gushing out of the spout of the kettle. She wondered whether
the temperature of the steam was higher than that of the water boiling in
the kettle. Comment
Water as ice has a cooling effect, whereas water as steam may cause severe
burns. Explain these observations.
Classify the following into osmosis/diffusion
(a) Swelling up of a raisin on keeping in water.
(b) Spreading of virus on sneezing.
(c) Earthworm dying on coming in contact with common salt.
(d) Shrinking of grapes kept in thick sugar syrup.
(e) Preserving pickles in salt.
(f) Spreading of smell of cake being baked through out the house.
(g) Aquatic animals using oxygen dissolved in water during respiration.
The non S I and S I units of some physical quantities are given in column
A and column B respectively. Match the units belonging to the same
physical quantity:
(A) (B)
(a) degree celsius (i) kilogram
(b) centimetre (ii) pascal
(c) gram per centimetre cube (iii) metre
(d) bar (iv) kelvin
(e) milligram (v) kilogram per metre cube
Match the physical quantities given in column A to their S I units given in
column B :
(A) (B)
(a) Pressure (i) cubic metre
(b) Temperature (ii) kilogram
(c) Density (iii) pascal
(d) Mass (iv) kelvin
(e) Volume (v) kilogram per cubic metre
Fill in the blanks:
(a) Evaporation of a liquid at room temperature leads to a——— effect.
(b) At room temperature the forces of attraction between the particles of
solid substances are———than those which exist in the gaseous state.
(c) The arrangement of particles is less ordered in the ——— state. However,
there is no order in the ——— state.
(d) ——— is the change of solid state directly to vapour state without going
through the ———state.
(e) The phenomenon of change of a liquid into the gaseous state at any
temperature below its boiling point is called———.
A sample of water under study was found to boil at 102°C at normal
temperature and pressure. Is the water pure? Will this water freeze at 0°C?
Comment
In which of the following conditions, the distance between the molecules of
hydrogen gas would increase?
(i) Increasing pressure on hydrogen contained in a closed container
(ii) Some hydrogen gas leaking out of the container
(iii) Increasing the volume of the container of hydrogen gas
(iv) Adding more hydrogen gas to the container without increasing the
volume of the container
(a) (i) and (iii)
(b) (i) and (iv)
(c) (ii) and (iii)
(d) (ii) and (iv)
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