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प्रश्न
What is a chemical change? Give two examples of chemical change?
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उत्तर
A chemical change is a permanent change in which the chemical composition of a substance is changed and a new substance is formed.
Examples:
Heating of copper carbonate
Formation of curd from milk
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संबंधित प्रश्न
How do the following help in bringing about a chemical change?
heat.
Give reason.
Acidic soil is treated with quick lime.
Fill in the blank:
During a chemical reaction transfer of ________ takes place.
Write true or false :
No new substance is formed during a chemical reaction.
Name the type of chemical reaction shown by the following equation:
NaOH + HCl → NaCl + H2O
Write your observation and a balanced equation in the case of the following substances being heated.
Ammonium dichromate.
A chemical reaction is often accompanied by external indications or characteristics which include –
- Colour change
- Effervescence or gas evolved
- Evolution or absorption of heat
- Formation of a precipitate.
With reference to each of the above indications, state the external indication seen during – Addition of dilute acid to an active metal.
Give balanced equation for the following conversion affected by heat alone on the substance:
Zinc carbonate to zinc oxide
Photosynthesis is a chemical reaction that takes place in the presence of ______.
We are advised to not to play with fireworks. Give reason.
