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प्रश्न
What do you understand by 'chemical reaction'?
उत्तर
A chemical reaction is the process of breaking the chemical bonds of the reacting substances (reactants) and making new bonds to form new substances (products).
A chemical change or chemical reaction occurs when particles collide. Collisions occur when reactants are in close contact or by supply of energy.
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संबंधित प्रश्न
State whether the following statement is true or false. In case a statement is false, write the corrected statement.
Iron and rust are the same substances.
Changes in which new substances are formed are called ______ changes.
Define; catalyst.
Give reason.
Wasp sting is treated with vinegar.
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
A solution of a substance ‘X’ is used for white washing Name the substance ‘X’ and write its formula.
Give reason for the following:
Silver nitrate solution is kept in coloured bottles.
What do you observe when Cobalt chloride paper is introduced in water vapour.
Give a chemical test to distinguish between the following gases.
H2 and O2
Distinguish by dilute sulphuric acid.
Sodium sulphide and sodium sulphite?
Give reason for the following:
Electrolytic decomposition of water is a reaction involving change of state.
Give balanced equation for the following conversion affected by heat alone on the substance:
Zinc carbonate to zinc oxide
Water boiling into water vapour is an example of chemical change.
Two chemical species X and Y combine together to form a product P which contains both X and Y
\[\ce{X + Y -> P}\]
X and Y cannot be broken down into simpler substances by simple chemical reactions. Which of the following concerning the species X, Y and P are correct?
(i) P is a compound
(ii) X and Y are compounds
(iii) X and Y are elements
(iv) P has a fixed composition
A student took a solution of copper sulphate in a beaker and put a clean iron nail into it and left it for about an hour.
Write a word equation for the chemical change, if any.
Iron and rust are the same substances.
Magnesium + oxygen → magnesium oxide.
2Mg + O2 → 2Mg O
Explain how the painting of an iron gate prevents it from rusting.
Write five changes in the characteristics of a substance that can take place during a chemical change.
What is thermochemical reactions?
