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प्रश्न
What is a chemical reaction?
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उत्तर
“Chemical reaction is a chemical change in which matter changes into a new substance or substances.”
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संबंधित प्रश्न
How would you show that setting of curd is a chemical change?
FILL IN THE BLANK
On reaction with sulphuric acid solution, barium chloride forms a white precipitate of ........ sulphate.
Name the type of chemical reaction shown by the following equation :
Fe2O3 + 2Al → Al2O3 + 2Fe
Choose the correct option from the bracket and explain the statement giving reason.
(Oxidation, displacement, electrolysis, reduction, zinc, copper, double displacement, decomposition)
The conversion of ferrous sulphate to ferric sulphate is ______ reaction.
Give an example of the following chemical change.
A reaction where colour change is noticed
What is observed in performing the following :
| Hydrogen | Oxygen | Carbon dioxide | Chlorine | |
| Litmus test | ||||
| Apply a burning splint to the gas | ||||
| Colour of gas | colourless | colourless | colourless | greenish-yellow |
| Odour of gas |
State the original colour of the following substance and colour of residue obtained after heating.
Zinc carbonate
What do you observe when Cl2 is passed through potassium iodide (KI) solution.
What do you observe when Cobalt chloride paper is introduced in water vapour.
Give a chemical test to distinguish between the following gases.
HCl and Cl2
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.
Complete the table given below.
| Addition of dil. H2SO4 to FeS | Odour of gas evolved |
State the following reaction represent oxidation or reduction.
\[\ce{Al->Al+++}\]
________ is a chemical substance which alters the speed of a chemical reaction.
Discuss how acid rain occurs due to emission of smoke from vehicles and industries?
Which of the following is not an “element + element → compound” type reaction?
Melting of wax is a change where a solid changes to liquid state. Give one more such change which you observe in your surroundings
Is the conversion of milk into ice cream a chemical change?
Explain how the painting of an iron gate prevents it from rusting.
______ is the chemical name of rust.
