5th std EVS chapter 24 substances,objects and energy l question and answer l explanation in marathi

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Environmental Studies -  5th Standard

24. Substances, Objects and Energy

Question And Answer

1) What’s the solution ?

(a) We need to make a sherbet quickly for some guests. But we only have sugar candy in the house.

Ans: We can pound sugar candy into fine powder. When the powder is fine. It will quickly dissolve in water. Therefore we can make sherbet quickly.

(b) We need to rub salt on a corncob but only salt crystals are available.

Ans: We can pound salt crystals. Either we can use mortar pestle or we can also crush the crystals of salt in a grinder. Such powdered salt can be easily applied on the corncob.

Q2. Use your brain power !

(a) Why do tablets of camphor decrease in size day by day ?

Ans: Tablets of camphor are in solid state. Camphor has a property to turn into gaseous state directly from a solid state. Therefore, camphor decreases in size gradually. One can also notice the fragrance of camphor as it turns into vapour.

(b) How do we save fuel by using public transport ?

Ans: Each automobile vehicle needs fuel either in the form of petrol, diesel or CNG. If all the people use a separate vehicle, the amount of fuel consumed would be much more. If many people start using a public transport, the fuel consumption would be reduced. A single bus or a train can carry many people and thus it can save lots of fuel.

Q3. Answer the following questions.

(a) When and why do clothes smell of naphthalene?

Ans: The naphthalene balls are continuously into small particles in the gaseous state. These particles settle down on the clothes in which they are kept. Therefore if naphthalene balls are kept for a long time in the clothes. They smell of naphthalene due to these particles.

(b) In which states is water found in nature ?

Ans: Solid, liquid and gaseous are the three states n which water is found in nature.

(c) What is the difference between the solid, liquid and gaseous states of a substance ?

Ans: The arrangements of the particles in different states of a substance are different. In solid state the particles are closely packed. In liquid state, the particles are slightly away from each other while in gaseous state they are not in contact with each other and are freely placed.

(d) What is meant by energy ?

Ans: The capacity to do the work is called energy.

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