Question

ng Answer Type Questions
33. (a) What is meant by a chemical reaction ? Explain with the help of an example
(b) Give one example each of a chemical reaction characterised by:
(i) evolution of a gas
(ii) change in colour
(iii) formation of a precipitate
(iv) change in temperature
(v) change in state.​

Answer 1

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Answer 2

Answer:

(a) A chemical reaction happens when one or more chemicals are changed into one or more other chemicals. Examples: iron and oxygen combining to make rust. vinegar and baking soda combining to make sodium acetate, carbon dioxide and water. ... many reactions that happen inside living things.

(b) I) Evolution of gas--- Reaction between zinc and dilute sulphuric acid

ii) Change in color--- Reaction between citric acid and purple colored potassium permanganate solution gives colourless solution.

iii) Formation of precipitate--- Reaction between potassium iodide and lead nitrate forms a yellow precipitate of lead iodide.

iv) Change in temperature: Reaction between zinc granules and dliute hydrochloric acid.

v) Change in state: Combustion of candle wax is characterized by a change in state from solid to liquid and gas.

Explanation:

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