EXERCISES
Q.1 - Give reason for the following observations.
(a) - Naphthalene balls disappear with time without leaving any solid.
ANS - Naphthalene undergoes sublimation easily i.e, the change of state of naphthalene from solid to gas takes place easily. Thus, naphthalene balls disappear with time without leaving any solid.
Q.2 - Arrange the following substances in increasing order of forces of attraction between the particles-water, sugar, oxygen.
ANS - oxygen-water-sugar.
Q.3 - Give tow reasons to justify-
(a) - water at room temperature is a liquid.
ANS - At room temperature (25 degree c), water is a liquid because it has the following characteristic of liquid.(i) - At room temperature water has a fixed volume that is it occupies the shape of the container in which it is kept.(ii) - At room temperature water flows.
Q.4 - What produces more severe burns, boiling water or steam?
ANS - Steam has more energy than cooling water. It possesses the additional latent heat of vaporization under force, burns produced by stem as more sever than those produced by boiling water .
