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प्रश्न
Fill in the blank
A change in which the substance can be brought back to its original state is called a _______ change.
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उत्तर
A change in which the substance can be brought back to its original state is called a reversible change.
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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.
Complete and balance the following chemical equations
Na + H2 O →
Fill in the blank
A catalyst either ................or ............... the rate of a chemical change but itself remains ............... at the end of the reaction.
MULTIPLE CHOICE QUESTIONS
Tick the most appropriate answer.
Which one of the following alters the rate of the chemical reaction without itself undergoing any change?
- temperature and Pressure
- concentration of reactants
- presence of catalyst
- none of these
Explain by writing a word equation.
Limestone powder disappears on adding to dilute hydrochloric acids.
Match the pairs.
| a. | Photosynthesis | i. | Tendency to lose electrons |
| b. | Water | ii. | Reactant in combustion process |
| c. | Sodium chloride | iii. | Chemical change |
| d. | Dissolution of salt in water | iv. | Covalent bond |
| e. | Carbon | v. | Ionic bond |
| f. | Fluorine | vi. | Physical change |
| g. | Magnesium | vii. | Tendency to form anion |
Give an example of a reaction where the following are involved
Electricity
Define a photochemical reaction.
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.
Explain,giving one example of the following chemical changes:
Reversible reaction
Explain the term ‘chemical reaction’ with special reference to – ‘reactants’ and ‘products’.
Complete the table given below.
| Addition of dil. H2SO4 to zinc | Test for gas evolved |
State the following reaction represent oxidation or reduction.
\[\ce{Ag->Ag+}\]
Give a balanced equation for a reaction involving the evolution of gas on the addition of dilute acid to calcium carbonate.
Give a balanced equation for the conversion of an ammonium salt to a basic gas.
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
A chemical change may involve –
The simplest method of preventing rusting of iron is to coat it with oil, grease, or paint. The reason being ______.
Write a note on the following:
Curdling of milk
