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प्रश्न
Fill in the blank:
The basic conditions necessary for a chemical reaction is _______
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उत्तर
The basic conditions necessary for a chemical reaction is close contact .
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संबंधित प्रश्न
Give one example that illustrates the following characteristics of a chemical reaction:
Change in state
How do the following help in bringing about a chemical change?
pressure.
What do you observe when iron nail is kept in copper sulphate solution for sometime.
MULTIPLE CHOICE QUESTIONS
Tick the most appropriate answer
Which of the following is a reducing agent?
- oxygen
- chlorine
- hydrogen
- none of these
MULTIPLE CHOICE QUESTIONS
Tick the most appropriate answer.
Reduction is a chemical reaction in which there is
- removal of hydrogen
- removal of oxygen
- addition of oxygen
- none of these
TRUE \ FALSE
Evaporation of water is a physical change. True or false ?
Complete the statement by filling the gaps using appropriate term from the terms given in the bracket.
(slow, coloured, arrow, fast, smell, milky, physical, product, chemical, reactant, covalent, ionic, octet, duplet, exchange, sharing, equality sign)
Rusting of iron is a ______ chemical change.
Give reason for the following:
Molybdenum is used in the manufacture of ammonia.
Give an example of the following chemical changes.
A reaction involving
(i) Change of state
(ii) formation of precipitate
State the original colour of the following substance and colour of residue obtained after heating.
Ammonium dichromate
Select the correct answer for the following options:
The gas obtained when potassium chlorate is heated in the presence of a catalyst.
Name the following:
The type of change physical or chemical involved – ‘during respiration in human beings’.
State the following reaction represent oxidation or reduction.
\[\ce{Ag->Ag+}\]
Name the solid residual product formed reaction and state its colour during – thermal decomposition of the following substance.
Ammonium dichromate.
Name the solid residual product formed reaction and state its colour during – thermal decomposition of the following substance.
Lead nitrate.
Silver metal can displace hydrogen gas from nitric acid.
Give two examples for the following case:
Chemical changes
Rusting of iron is ______.
Match the following:
| Column I | Column II | ||
| 1. | Burning of coal | a. | Rusting |
| 2. | Painting of a surface | b. | Evaporation |
| 3. | Dipping iron in the water | c. | Chemical change |
| 4. | Salt from seawater | d. | Prevention of rusting |
Acid rain is a result of ______.
