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प्रश्न
Define a chemical change. Give two examples of the above changes.
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उत्तर
A permanent change in which new substances are formed whose composition and properties are completely different from those of the original
substances.
Chemical change:
(i) Burning of wood.
(ii) Breathing.
संबंधित प्रश्न
Classify the following as chemical or physical change:
Burning of paper and wood
Classify the changes involved in the following process as physical or chemical changes:
Photosynthesis
Fill in the blank.
A new substance is formed in a ............... change.
Write true or false for the statement
A natural change can also be a desirable change
Write short answer.
Give an example of desirable change which can also be undesirable
State the various conditions that favour the process of evaporation.
Classify the following changes as physical or chemical:- photosynthesis in plants
Tick (√) the correct alternative from the choice given for the following statement
Which one of the following is volatile in nature ?
Fill in the blank
Heat is ________ by a gas during the process of condensation.
State one instance where water undergoes a physical change and one in which it undergoes a chemical change.
Separate the following into physical and chemical changes :
Sublimation of a solid, Decomposition of water into hydrogen and oxygen by passing electric current, Formation of clouds, Making a fruit salad from raw fruits, Dissolving carbon dioxide in water
Which of the following are physical changes and which are chemical changes?
Burning of candle wax, Melting of candle wax, Mixing of iron filings and sand, Burning of wood, Breaking a piece of chalk, Burning a piece of paper, Cutting a piece of paper.
Give a reason why
Change of seasons is a periodic change while the change of weather is a non-periodic change.
Is a change of state of matter – a physical or a chemical change. Give reasons.
Give a reason why – Heating a platinum wire is a reversible change but, heating a magnesium wire is an irreversible change.
Give a reason why rusting of iron is a chemical change but, the magnetization of iron is a physical change.
Select the chemical changes from the following list of changes
Respiration in mammals.
Select the chemical changes from the following list of changes
Glowing of an electric bulb.
Give the reason why the following is considered as chemical changes.
Sulphur when burnt in air evolves a gaseous acidic product.
Which of the following is a physical change?
