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प्रश्न
Fill in the blank.
Melting of ice is a _______ change.
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उत्तर
Melting of ice is a physical change.
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संबंधित प्रश्न
How do the following help in bringing about a chemical change?
pressure.
Write the missing reactants and products and balance the equations.
\[\ce{KClO3 ->[heat]}\] ___________+ ____________
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
What are chemical reactions?
Fill in the blank
A new substance is formed in a _______ change.
Write true or false :
When iron and sulphur are heated together a grey mass is formed which is attracted by a magnet .
A chemical equation is a statement that describes a chemical change in terms of
Explain by writing a word equation.
Hard water gets softened on mixing with a solution of washing soda.
Show with the help of diagram of electronic configuration how the following compound is formed from the constituent atoms.
Water
Explain the term reactant and product giving examples.
Define a photochemical reaction.
Write the chemical reaction where the following changes are observed.
Physical state is changed
What do you observe? When
Water is added to the quick lime.
Give examples of exothermic reactions i.e. heat evolved in each of the following:
(a) reaction between a solid and a liquid
(b) reaction between two gases
Give two examples of exothermic reactions seen in everyday life.
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 |
Complete the table given below.
| Addition of dil. H2SO4 to zinc | Test for gas evolved |
What kind of a change is associated with decaying of a plants?
