Improvement in Food Resources — Science STD 9 — Question

How can you obtain pure water from a salt-water mixture (or salt-solution)? Draw a meat and labelled diagram of the apparatus you would use to obtain pure water from a salt-water mixture (or salt-solution).

A sound producing body is at considerable distance from a man. There can be four different media W, X, Y and Z between the sound producing body and the man. The medium X brings the sound to man most quickly whereas medium Z takes the maximum time. The time taken by medium W in bringing sound to man is less than that of X but more than that of Z. The medium Y, however, fails to bring the sound from the sound producing body to the man. Which medium could be the one:

1. Having no fixed shape and no fixed volume?
2. Having a fixed volume but no fixed shape?
3. Having the same composition as that on the moon?
4. Having a fixed shape and a fixed volume?

Show by an activity that the gases are highly compressible as compared to liquids.

Explain the mechanism of compost formation.

Define relative density of a solid. State its unit. How is it related to its density? Write mathematical expression for relative density. What conclusion do you draw if relative density of a substance is (a) greater than 1, (b) less than 1 and (c) equal to 1?

State the main points of difference between homogeneous and heterogeneous mixtures.

Describe the method of separating a mixture containing common salt, sand and ammonium chloride.