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प्रश्न
Give reason for the following:
Even though rusting is an exothermic reaction, the heat evolved when an iron nail rusts is unnoticeable.
उत्तर
Rusting of iron – the reaction is slow and the heat evolved is very less, hence unnoticeable.
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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.
Formation of manure from leaves is a physical change.
State whether the following statement is true or false. In case a statement is false, write the corrected statement.
Condensation of steam is not a chemical change.
How do the following help in bringing about a chemical change?
pressure.
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
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TRUE \ FALSE
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NaOH + HCl → NaCl + H2O
Complete the following table and write your observations.
|
Hydrogen sulphide |
Ammonia |
Sulphur dioxide |
Hydrogen chloride |
|
|
Shake the gas with red litmus solution |
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|
Shake the gas with blue litmus solution |
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|
Apply a burning splint to a gas |
Name: A brown gas
Name: A greenish-yellow gas.
What do you observe when Cobalt chloride paper is introduced in water vapour.
Write your observation and a balanced equation in the case of the following substances being heated.
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Complete the table given below.
| Addition of dil. H2SO4 to KHCO3 | Name of residue obtained |
State the following reaction represent oxidation or reduction.
\[\ce{Cu++->Cu}\]
State the following reaction represent oxidation or reduction.
\[\ce{Al->Al+++}\]
Give a balanced equation for the conversion of an ammonium salt to a basic gas.
Select the correct answer from the options given below:
State the gaseous product formed, when
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Differentiate between the following:
Neutralization reaction and a precipitation reaction.
Circle the odd one out. Give reason for your choice
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Chemical change is a temporary change.
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?
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Write a note on the following:
Curdling of milk
______ is a chemical substance is used in whitewashing.
