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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 do the following help in bringing about a chemical change?
pressure.
Complete and balance the following chemical equation:
\[\ce{Pb(NO3)2 ->[Heat]}\]
Write the missing reactants and products and balance the equations.
................+ HCI `→` NaCI + `"H"_2"O"` + .........................
Write true or false :
No new substance is formed during a chemical reaction.
Give a chemical test to distinguish between the following gases.
HCl and H2S
Distinguish by heating the following in dry test tubs.
Zinc carbonate, Copper carbonate and lead carbonate.
Distinguish by heating the following in dry test tubs.
Copper Sulphate and copper carbonate
Give a word equation for the following reaction.
A salt which reacts with ammonium hydroxide to give a reddish brown precipitate.
Name the following:
The products obtained during ‘photosynthesis’ – which is a chemical change.
Complete the table given below.
| Heat on ammonium dichromate | Name of neutral gas evolved |
Complete the table given below.
| Heat on copper carbonate | Test for gas evolved |
Explain the Silver nitrate solution is kept in coloured reagent bottles in the laboratory.
Give a balanced equation for the conversion of a soluble lead salt to an insoluble lead salt – formed as a white precipitate.
What happens when cane sugar is strongly heated? Mention any two changes in it.
Assertion: The formation of iron oxide from iron is a chemical change.
Reason: For the rust to form from iron, it must be exposed to air and water.
The simplest method of preventing rusting of iron is to coat it with oil, grease, or paint. The reason being ______.
______ occurs in the absence of air and in the presence of micro-organisms such as yeast.
Write the characteristics of chemical change.
Both CO2 and H2 gases are ______.
