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प्रश्न
Explain the term ‘chemical reaction’ with special reference to – ‘reactants’ and ‘products’.
उत्तर
A chemical reaction involves the breaking of existing bonds between atoms or groups of atoms of the reactants and leading to formation of new bonds forming new substances called the products.
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संबंधित प्रश्न
Fill in the blanK
A .............is a substance which changes the rate of a chemical reaction without undergoing a chemical change.
Give reason.
Wasp sting is treated with vinegar.
FILL IN THE BLANK
A .............. change is a temporary change.
TRUE \ FALSE
Electrolytic refining is a method in which a thin coating of a metal is done over another metal.
Explain the following reaction with one suitable example of Displacement reaction.
Name the type of chemical reaction shown by the following equation:
CaCO3 → CaO + CO2
Name the type of chemical reaction shown by the following equation:
2Mg + O2 → 2MgO
Complete the statement by filling the gaps using appropriate term from the terms given in the bracket.
(slow, coloured, arrow, fast, smell, milky, physical, product, chemical, reactant, covalent, ionic, octet, duplet, exchange, sharing, equality sign)
The spoiling of food is a chemical change which is recognized from the generation of certain ______ due to it.
State the conditions necessary for a chemical change or reaction.
Write the chemical reaction where the following changes are observed.
Colour change is noticed
Write the chemical reaction where the following changes are observed.
Precipitate is formed
Multiple choice:
Which of the following is not a characteristic of a chemical change?
Give an example of the following chemical changes.
A reaction where colour change is noticed.
Give a chemical test to distinguish between the following gases.
H2 and O2
Give a word equation for the following reaction.
A compound which on heating shows – colour change from brown to yellow.
Name the solid residual product formed reaction and state its colour during – thermal decomposition of the following substance.
Copper nitrate.
______ gas causes tears in our eyes while cutting onions.
______ is not a chemical change.
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.
Mention the various conditions required for a chemical reaction to occur.
When lithium metal is placed in hydrochloric acid, _______ gas is evolved.
The water we drink is a combination of hydrogen and oxygen.
Arrange the following statements in correct sequence:
- One side is water-loving and other water-hating molecules.
- When you agitate the cloth, the dirt is surrounded by many molecules and taken away from the cloth.
- The dirt surrounded by the detergent molecules floats in the water making it dirty.
- Finally, the cloth is clean.
- The detergent molecules have two sides.
- Water hating goes and joins with dirt and oil in the cloth while the water-loving joins with the water molecules.
If you leave a piece of iron in the open for a few days, it acquires a film of brownish substance, called rust.
Can you change rust back into iron by some simple method?
Heat may evolve or be absorbed during a ______ change.
Is the conversion of milk into ice cream a chemical change?
Write the equation for the process of formation of rust.
Chemical changes are important in our day-to-day life. Give examples.
Write a note on the following:
Fermentation
What is thermochemical reactions?
