Advertisements
Advertisements
Question
Which of the following are chemical changes ?
- decaying of wood
- burning of wood
- sawing of wood
- hammering of nail into wood
Options
(i) and (ii)
(ii) and (iii)
(iii) and (iv)
(i) and (iv)
Solution
(i) and (ii)
The processes in statements (i) and (ii) are chemical changes because decaying and burning causes formation of new compounds; thus they are chemical reactions. The processes in statements (iii) and (iv) are physical changes where no new compounds are formed.
APPEARS IN
RELATED QUESTIONS
Classify the following as chemical or physical change:
Burning of paper and wood
Classify the changes involved in the following process as physical or chemical changes:
Photosynthesis
What do you observe when :
lighted match stick is brought near the mouth of the test tube containing hydrogen gas.
Fill in the blank
Revolution of the earth around the sun is a ________ change.
Write true or false
A natural change can also be a desirable change.
Give two examples of periodic changes.
Explain the term – ‘sublimation’. Is sublimation of naphthalene – a physical or a chemical change. Give reasons.
Match the examples of changes in List I with the correct.
| List I | List II |
| 1. Expansion of a steel rod on heating | A: Physical change |
| 2. Rotting of eggs | B: Chemical change |
| 3. Milk turning sour | |
| 4. Tarnishing of copper | |
| 5. Separation of naphthalene from a mixture of naphthalene and sodium chloride. |
Iron pipes coated with zinc do not get rusted easily.
Mention some of the different conditions needed for chemical changes to occur.
