physical and chemical change extra question
Answers
Answer:
you have to do their definitions and activities because activities are must in exams
Explanation:
Classify the following processes into physical or chemical changes:
(i) Beating of aluminium metal to make aluminium foil.
(ii) Digestion of food.
(iii) Cutting of a log of wood into pieces.
(iv) Burning of crackers.
Write word equations for two chemical reactions with the help of materials given in the box.
Air, copper sulphate, iron, vinegar, iron oxide, carbon dioxide, iron sulphate, copper, lime water, water
Explain the following:
(a) Lime water turns milky on passing carbon dioxide gas into it.
(b) Bubbles are produced when acetic acid is added to a solution of sodium hydrogencarbonate.
Long Answer Type Questions
Give two examples for each of the following cases:
(a) Physical changes which are reversible.
(b) Physical changes which are not reversible.
(c) Chemical changes.
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.
If you leave a piece of iron in the open for a few days, it acquires a film of brownish substance, called rust.
(a) Do you think rust is different from iron?
(b) Can you change rust back into iron by some simple method?
(c) Do you think formation of rust from iron is a chemical change?
(d) Give two other examples of a similar type of change.
A student took a solution of copper sulphate in a beaker and put a clean iron nail into it and left it for about an hour.
(a) What changes do you expect?
(b) Are these changes chemical in nature?
(c) Write a word equation for the chemical change, if any