Question

a chemical change may occurs by one of the following changes.
a) Evolution of gas
b) change of colour
c) absorption of energy
d) evolution of heat
e) change of smell

Give an example for each

Answer 1

evolution of gas - when baking soda mixed with lemon juice carbon-dioxide gas are formed

Answer 2

Hope this helps you...
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Evolution of gas - when any reaction takes place there is formation of a new gas that is nnot linked to that composition . Especiall oxides of oxygen are evolved when a thing is burned or in other reactions.