Materials into Groups
any two objects made up of opaque materials.
Ans. wooden doors and
Q15. What is
common between oil and water?
Ans. Both are in liquid
two things made from leather.
Ans. belt and hand-bag
name of any three metals.
Ans. Iron, Aluminium and
few things made up of plastic.
Ans. cups, plates, toys,
Q19. Why water
is considered as a universal solvent?
Water is capable of dissolving most of the substances in it. That is why it is
known as universal solvent.
Q20. Why does a coin sink in water?
Object with higher density than water will sink. A coin is made up of metal.
Density of metal is higher than water. That’s why coin sinks in water.
Q21. Why are
cooking utensils made of metal but their handles of plastic or wood?
Ans. Cooking utensils have
wood or plastic handles to prevent us from burning our hands when utensils are
Q22. Why oil does not dissolve in water?
Oil does not dissolve in water because the space between the molecules of water
is not occupied by the oil.
Q23. Why some material loses their shine and appears dull?
Due to the action of air and moisture on them, a dull layer of some other
compound appears on them. Thus material loses their shine and appears dull.
Q24. We can
group things in more than one way. Explain.
Ans. We can group things in more than one way because
one object can have more than one property.
and carbon dioxide are slightly soluble in water. What is the importance of
each of these gases in nature?
Ans. Oxygen and carbon
dioxide gas dissolved in water are needed for the survival of animals and
plants that live in water.
density. How is it related to floating and sinking in water?
Ans. The degree of
compactness of a substance is called density. The object which is denser than
water will sink whereas object which is less dense than water will float.
does sugar dissolve in water?
Ans. Water molecules
surround the tiny sugar cubes and hit them. This weakens the attractive forces
of the surrounding molecules and pulls them into the solution.
Q28. Why in
departmental stores all brands of shampoos and soaps are kept together while
all pulses and kitchen items are kept at one place?
Ans. This is done, so that customer can easily
pick the things needed and compare values of different brands available.
Q29. What is
Ans. The process of
grouping things together on the bases of some similar characteristics is called