12. Which of the following is not a reversible change?
(1) The vaporisation of water
(2) The melting of iron
(3) The freezing of water
(4) The burning of kerosene
13. Statement-I : A change which can be reversed is called a reversible change.
Statement-II : Falling of leaves from a tree is reversible change.
(1) Both statements I and II are correct.
(2) Both statement I and II are incorrect.
(3) Statement I is correct and statement II is incorrect.
(4) Statement I is incorrect and statement II is correct.
14. Which of the following is not an irreversible change?
(1) The ripening of a mango
(2) The curdling of milk
(3) The condensation of water vapour
(4) The slaking of lime
15. Which of the following is not a reversible change?
(1) Heating of water to steam
(2) Cooking of egg to scrambled eggs
(3) Heating of wax to molten wax
(4) Cooling of water to ice
II. SUBJECTIVE TYPE QUESTIONS :
16. Give some examples from daily life where expansion of metal by heating is used and also explain it.
17. Most physical changes are reversible give reasons with two examples?
18. Write the various characteristics of
(1) Physical change (2) chemical change
III. HOTS (High Order Thinking Skills) :
19. Explain why:
(i) Printing is an irreversible change.
(ii) Ironing of cloth is reversible change.
(iii) Melting of wax is a reversible change.
20. Differentiate between reversible and irreversible change?
Answers
Answer:
Q12 4) The burning of Kerosene
Answer
Ans 12 - 1 , 3 is reversible change = 2,4 is not reversible change
ans 13- 3 √
Ans 14-=2 is not an irreversible change
Ans 15- 4 is not an reversible change
Q2 - Subjective type answer
Ans 16- in contruction of house ,
Ans 17-(i) Melting of ice: During this change, the water changes from its solid form to liquid form. It can be solidified again. The water remains water in both cases hence this is a reversible change
Ans 18- chemical changes = there are five characteristics
° colour change
° Production of an odor.
° change of temperature
° evolution of a gas < formation of bubles >
° formation of solid
Physcial change = Types of physical changes include boiling, clouding, dissolution, freezing, freeze-drying, frost, liquefaction, melting, smoke and vaporization.
° Boiling Liquids. ...
° Clouding and Condensation. ...
° Dissolution or Dissolving. ...
° Freezing or Solidification. ...
° Freeze-drying or Lyophilization. ...
° Frost Formation. ...
° Liquefaction Changes.
Q -3 Hots
ans 19
Ans (i)= Is printing a reversible or an irreversible change? Answer: Printing is an irreversible change because we cannot separate and collect the printing ink after printing
Ans (ii) =: Ironing removes the wrinkles of the clothes, which can come back in the same condition. Hence, ironing of a cloth is a reversible change
Ans (iii) = The burning of candle wax to form hydrocarbons is a chemical change. The burning of the candle wick is a chemical/irreversible change. While the melting of wax is reversible, It can be again used after it has been melted as it gets back to its original form once the temperature gets lower
Q-20
Ans Image result for Differentiate between reversible and irreversible change?
All changes in the world are one of the two types – Reversible changes and irreversible changes. A change which can happen backward, that is, can be reversed is called a reversible change. ... A change which cannot happen backward, that is, it cannot be reversed is called an irreversible change.
Explanation: