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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.
Iron pipes coated with zinc do not get rusted easily.
TRUE \ FALSE
Temperature at which a liquid starts boiling is known as the boiling point of that liquid. True or false ?
Differentiate between in Chemical reaction and chemical equation.
Fill in the blank:
In some chemical reactions an insoluble ________ is formed when two solutions are mixed.
Write true or false :
When iron and sulphur are heated together a grey mass is formed which is attracted by a magnet .
Balancing a chemical equation is based on
Name the type of chemical reaction shown by the following equation:
Fe + CuSO4 → FeSO4 + Cu
Out of sodium and sulphur which is a metal? Explain its reaction with the oxygen.
Explain by writing a word equation.
Hard water gets softened on mixing with a solution of washing soda.
Name the gases which Turn moist red litmus blue.
What do you observe when Cl2 is passed through potassium iodide (KI) solution.
Give a chemical test to distinguish between the following gases.
H2 and O2
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Ammonium chloride
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Complete the table given below.
| Flame test for calcium chloride | Acid used for flame test |
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Copper nitrate.
Circle the odd one out. Give reason for your choice
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______ change results in the change of the substance.
Classify the following as physical or chemical properties
Zinc dissolves in hydrochloric acid with the evolution of hydrogen gas.
Which of the following is/are true when milk changes into curd?
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- It changes the taste.
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Choose the correct option from below:
Rusting of iron is ______.
When magnesium is burnt in the air, a new substance is formed which is ______.
______ occurs in the absence of air and in the presence of micro-organisms such as yeast.
The chemical formula of rust is ______.
Give an example where heat, light, and sound are produced during a chemical change.
Assertion (A): Cutting paper into very small pieces is an irreversible change.
Reason (R): Physical changes are always reversible.
Define the following term:
Chemical change
