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प्रश्न
Fill in the blank:
During a chemical reaction transfer of ________ takes place.
उत्तर
During a chemical reaction transfer of energy takes place.
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संबंधित प्रश्न
How do the following help in bringing about a chemical change?
catalyst .
What are (i) positive catalysts and (ii) negative catalysts? Support your answer with one example for each of them.
Complete and balance the following chemical equations:
N2 + O2 →
What are oxides ?
FILL IN THE BLANK
Negatively charged ions are called ..........
Name three reducing agents ?
Choose the correct option from the bracket and explain the statement giving reason.
(Oxidation, displacement, electrolysis, reduction, zinc, copper, double displacement, decomposition)
To prevent rusting, a layer of ______ metal is applied on iron sheets.
Explain by writing a word equation.
Respiration is a chemical change.
What is a chemical reaction?
Explain,giving one example of the following chemical changes:
Reversible reaction
Multiple choice:
Which of the following is not a characteristic of a chemical change?
What do you understand by 'chemical reaction'?
What do you observe? When
Barium chloride is added to sodium sulphate solution
Give an example of the following chemical changes.
A reaction where colour change is noticed.
Complete and balance the following reaction:
NaCl(aq) + AgNO3(aq) →
Complete and balance the following reaction:
Pb(NO3)2 + KI →
What do you observe when H2S is passed through a lead nitrate solution.
Write your observation and a balanced equation in the case of the following substances being heated.
Ammonium chloride
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.
| Heat on iodine crystals | Colour of vapours evolved |
What is the use of indicator?
Write some materials prepared by chemical changes.
A chemical change may involve –
State whether the following statements are true or false:
When a candle burns, both physical and chemical changes take place.
If you leave a piece of iron in the open for a few days, it acquires a film of brownish substance, called rust.
Do you think the formation of rust from iron is a chemical change?
The simplest method of preventing rusting of iron is to coat it with oil, grease, or paint. The reason being ______.
______ are substances that speed up the process of a chemical change and it will not undergo any change during the course of the reaction.
Iron and rust are the same substances.
Write the characteristics of chemical change.
