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प्रश्न
Define the following term:
Chemical change
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उत्तर
A chemical change is a permanent change in which the chemical composition of a substance is changed and one or more new substances with different chemical compositions and different properties are formed.
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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.
Complete and balance the following chemical equations:
Zn + `"H"_2"SO"_4` `→`
(dil)
MULTIPLE CHOICE QUESTIONS
Tick the most appropriate answer.
Compounds, which in their molten state allow an electric current to pass through them are called
- electrolytes
- non-electrolytes
- non-conductors
- none of these
Write true or false :
No new substance is formed during a chemical reaction.
Write true or false :
Hydrogen sulphide has rotten egg smell .
Complete and balance the following reaction:
NaCl(aq) + AgNO3(aq) →
Give a chemical test to distinguish between the following gases.
H2 and CO2
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.
What kind of a change is associated with decaying of a plants?
Anaerobic bacteria digest animal waste and produce biogas (Change – A). The biogas is then burnt as fuel (Change – B). The following statements pertain to these changes. Choose the correct one.
