Which of the following is a physical change?

A chemical change may involve

A man painted his main gate made up of iron, to

Galvanisation is a process used to prevent the rusting of which of the following?

Paheli's mother made a concentrated sugar syrup by dissolving sugar in hot water. On cooling, crystals of sugar got separated. This indicates a

When carbon dioxide is passed through lime water, it turns milky due to the formation of _________

Two methods by which rusting of iron can be prevented are __________ and ___________

A physical change is generally _________

The presence of _________ in seawater makes the process of rust formation on ships faster

The process of depositing a thin layer of zinc on iron object is called ________

Iron pipes coated with zinc do not get rusted easily.

When a candle burns, both physical and chemical changes take place.

Stretching of rubber band is not a physical change.

A blue deposit is formed on an iron nail when dipped in copper sulphate solution.

The colour of iron sulphate solution is green.

What kind of change is shown by tearing of paper?

Melting of wax is a change where a solid changes to liquid state. Give one more such change which you observe in your surroundings.

How can you say that ripening of a fruit is a chemical change?

What is the nature of magnesium oxide solution?

Suggest two methods to prevent rusting.

Classify the changes involved in the following processes as physical or chemical changes.
(a) Photosynthesis
(b) Dissolving sugar in water
(c) Burning of coal
(d) Melting of wax
(e) Beating aluminium to make aluminium foil
(f) Digestion of food

Explain why burning of wood and cutting it into small pieces are considered as two different types of changes.

Describe how crystals of copper sulphate are prepared.

Explain how painting of an iron gate prevents it from rusting.

Describe two changes that are harmful. Explain why you consider them harmful? How can you prevent them?

Give an example of a chemical reaction for each of the following situations:
(a) A change in colour is observed.
(b) A gas is evolved.
(c) Sound is produced.

Rahul was a student of Class VII. His father purchased a new bicycle for him on his birthday. After few months, he found that the cycle chain and even the handle gets rusted. His father advised him to apply a coating of paint to the cycle and not to keep it in the open in future. Now, answer the following questions:
(a) Why his cycle gets rusted?
(b) What do you mean by rusting of iron?
(c) What values are shown py Rahul's father?