10.Solids, liquids and gases

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10 . Solid liquid and gases Q. 5.Read the following two statements and choose the correct option.  Statement1- liquid have definite volume and shape.  Statement 2- The molecules of solid are not very closely packed.  Ans. Both statements 1 and 2 are incorrect.  Q6. Short answer type questions a . Why is melting of butter a physical change?   Ans. Melting of butter is a physical change as no new substance is fromed and there is only change in the state of matter on cooling the melted butter gets solidified.  b. How can we change a matter from its one state to another?  Ans. We can change a matter from its one state to another by heating and cooling.  c. What is a solution? Give an example.  Ans. When solutes ( suger or salt) dissolve in solvent like water, the mixture then formed is known as solution for example ,sugar inbwater salt in water etc.  d. Define a solute and a solvent.  Ans. The liquid in which other substance...

8.our solar system

science std 4
Stateboard question with ans. 
Time to Answer
Fill in  the blanks. 
1. Mercury is the smallest planet. 
2.Venus is also known as the morning star. 
3.Moon is a heavenly body that moves around planets. 
4.Mars is also called the red planet. 
5.Jupiter is the largest planet. 


Fill in the blanks. 
1.The Rotation of the earth causes day and night. 
2.The revolution of the earth causes seasons
3. The sunbrises from east and sets in the West
4.The outermost hard layer of the earth is called crust

5. Short answer type questions
Ans. Orbit is a curved path followed by a planet or an object as it moves around another planet, star, moon etc
Ans. 
.         Star                                  planet                  .
1.They are big               1.They are slow moving
   heavenly bodies          heavenly bodies that                                                move in an orbit                                                      around the sun.         . 
2. Sun is the only star   2.They are only 8 planet
Present in the solar         in the solar system
System .                                                                 . 
3.They have their own  3. They do not have 
heat and light.                  light of their own.       . 

Ans. Saturn and Jupiter have more than 60 moons. 

Ans. Our earth complete one revolution in 365 1/14 days, which is called asolar year. 

6.Long answer types questions
Ans. Scientists believe that the earth was a huge ball of dust and burning gasses in the beginning. It kept on spinning,. As it spun around for millions of years, it's outer surface became cold and hard some of the hot gasses escaped, while some were trapped inside. So the outer surface of the earth is hard but the inside has hot molten material this is how the earth come into existence. 

Ans. The earth crust is made up of rocks and mineral. It is also coverd with oceans and seasy and farms and living beings. 

Ans. The revolution of the earth causes seasons. The earth revolves around the sun how ever during it's revolution, it's axis always remains tilted at an angel. As a result, at certain times of the year, the North Hemisphere is tilted towards the sun, while the southern Hemisphere is tilted away from it. At other times, the southern Hemisphere is tilted towards the sun, while the Northern Hemisphere is tilted away from it. The hemisphere which is tilted towards the sun gets the sun's rays directly & so it is warmer than the other hemisphere which is tilted away from the sun gets slanting rays from the sun & has winter. 

d. Why is the season in the Northern Hemisphere always different from that in the southern Hemisphere? 
Ans. The season in the northern hemisphere is always different from that in the southern hemisphere because of the following resons. 
1. When the North hemisphere is tilted to wards the sun it has summer. At there time the southern hemisphere tilted away from the sun has winter. 
2. When the northern hemisphere is tilted away from the sun it has winter & the southern hemisphere has summer. 

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