Changes around us

Which one of the followings is an example of irreversible change?

• A)  Melting of wax

• B)  Stretching of a rubber band

• C)  Melting of coal tar

• D)  Ripening of fruits

Which one of the following statements is correct? Statement 1: Increasing of our body temperature is a reversible change Statement 2: Dissolution of gasses like oxygen and carbon dioxide in water is irreversible changes.

• A)  Statement 1

• B)  Statement 2

• C)  Both statements are correct

• D)  Both statements are incorrect

Which one of the following is an example of chemical change?

• A)  Burning of wax

• B)  Stretching a metal spring

• C)  Breaking of glass

• D)  All of these

In which one of the following kind of changes, molecules of a substances undergo changes?

• A)  Physical changes

• B)  Chemical changes

• C)  Reversible changes                                       

• D)  All of these

Study the table given below. Which of the above changes is wrongly classified?

                                         

• W

• X

• Y

• Z

Which of the following is NOT a feature of a physical change?

• A)  It can be reversible.

• B)         It is temporary.

• C)         No new substance is formed.      

• D)         The composition of the substance changes.    

Iron rim will fit on the wooden wheel by heating, because;

• Heat expands the iron rim

• Heat will contract the iron rim

• Heating will make the rim more stronger

• None of the above

Mark the incorrect statement.     

• A)  Melting of wax is a physical change while burning of wax in a candle is a chemical change.                 

     

• B)  Metals expand on heating while contract on cooling. Both are physical changes.                        

• C)  Composition of matter changes during a chemical change while it remains same during a physical change.

• D)  High and low tides in sea are the examples of non-periodic changes while growth of a tree is a periodic change.