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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.
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उत्तर
Rusting of iron – the reaction is slow and the heat evolved is very less, hence unnoticeable.
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संबंधित प्रश्न
How do the following help in bringing about a chemical change?
catalyst .
MULTIPLE CHOICE QUESTIONS
Tick the most appropriate answer
Which of the following is a reducing agent?
- oxygen
- chlorine
- hydrogen
- none of these
TRUE \ FALSE
Electrolytic refining is a method in which a thin coating of a metal is done over another metal.
What are the characteristics of a chemical reaction ? A chemical reaction is characterised by an irreversible change in which a new substance is formed.
State what you would observe when the following substance is heated in a glass test tube Copper (II) carbonate Red lead .
Give an example of a reaction where the following are involved
Heat
Give an example of the following chemical change.
Two solids combine to form a liquid
What do you observe when HCI is passed through a silver nitrate solution.
What do you observe when dilute sulphuric acid is added to the following:
Sodium Sulphide
Give a word equation for the following reaction.
A compound which on heating shows – colour change from brown to yellow.
Give reason for the following:
A characteristic change of colour is seen when a piece of iron is added to copper [II] sulphate solution.
State the following reaction represent oxidation or reduction.
\[\ce{H->H+}\]
Give a balanced equation for a reaction involving the evolution of gas on the addition of dilute acid to calcium carbonate.
Complete the statement by filling in the blank with the correct word:
The reddish-brown precipitate obtained during a double decomposition precipitation reaction between an iron salt and alkali is __________.
The chemical change is ______.
What is the role of a catalyst in a chemical reaction?
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.
Heat may evolve or be absorbed during a ______ change.
______ are substances that speed up the process of a chemical change and it will not undergo any change during the course of the reaction.
The reaction of H2 gas with oxygen gas to form water is an example of ______.
