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प्रश्न
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 water to quicklime.
उत्तर
Addition of water to quick lime: Hissing sound accompanied by a lot of heat (boiling).
APPEARS IN
संबंधित प्रश्न
Give one example that illustrates the following characteristics of a chemical reaction:
Change in state
How do the following help in bringing about a chemical change?
light.
Give reason.
Acidic soil is treated with quick lime.
Give reason.
Wasp sting is treated with vinegar.
MULTIPLE CHOICE QUESTIONS
Tick the most appropriate answer.
Reduction reaction is the exact opposite of
- displacement reaction
- decomposition reaction
- oxidation reaction
- none of these
FILL IN THE BLANK
A .............. change is a temporary change.
Explain the type of reactions on the basis of the direction of reaction.
How is a strong electrolyte different from a weak electrolyte?
Write true or false :
Hydrogen sulphide has rotten egg smell .
Write true or false.
A chemical equation gives only qualitative information of a chemical reaction.
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.
Define Photochemical reaction
Give an example
Give reason for the following:
Silver nitrate solution is kept in coloured bottles.
Give reason for the following:
Blue solution of copper sulphate changes to green when a piece of iron is added to this solution.
When hydrogen burns in oxygen, water is formed; when electricity is passed through water, hydrogen and oxygen are given out. Name the type of chemical change involved in the two cases.
What do you observe? When
Water is added to the quick lime.
State the original colour of the following substance and colour of residue obtained after heating.
Copper carbonate
Write your observation and a balanced equation in the case of the following substances being heated.
Ammonium chloride
Select the correct answer for the following options:
The gas which reacts with oxygen to give a neutral liquid.
State the following reaction represent oxidation or reduction.
\[\ce{Ag->Ag+}\]
Give a suitable example with an equation to show the representation of a chemical reaction.
Select the correct answer from the options given below:
State the gaseous product formed, when
An ammonium salt reacts with an alkali.
Higher order Thinking question
Peeled and unpeeled banana does not look the same. Does that mean peeling banana is a chemical change?
Discuss how acid rain occurs due to emission of smoke from vehicles and industries?
The changes in which new substance with new chemical properties are formed are ______.
Which of the following are chemical changes?
(i) Decaying of wood
(ii) Burning of wood
(iii) Sawing of wood
(iv) Hammering of a nail into a piece of wood
The simplest method of preventing rusting of iron is to coat it with oil, grease, or paint. The reason being ______.
______ is a chemical substance is used in whitewashing.
