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प्रश्न
Explain the following reaction with one suitable example of Combination reactions .
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उत्तर
Combination reactions : In this reaction two or more substances combine to form a new substance, e.g. Burning of hydrogen in air.
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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.
Complete and balance the following chemical equations:
Zn + `"H"_2"SO"_4` `→`
(dil)
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
FILL IN THE BLANK
Negatively charged ions are called ..........
Write true or false :
No new substance is formed during a chemical reaction.
State what you would observe when the following substance is heated in a glass test tube Copper (II) carbonate Red lead .
Name the type of chemical reaction shown by the following equation:
CaCO3 → CaO + CO2
Name: Gas with rotten egg smell.
State the original colour of the following substance and colour of residue obtained after heating.
Zinc carbonate
What do you observe when dilute sulphuric acid is added to the following:
Sodium Sulphide
On heating which of the following substances i.e. copper carbonate, zinc carbonate, washing soda, copper sulphate, zinc nitrate, copper nitrate, lead nitrate, ammonium chloride and ammonium dichromate – relate to the reaction given below.
A coloured substance which leaves a black residue and evolves two gases one of which is acidic and coloured and the other neutral and colourless.
Select the correct answer from the options given below:
State the gaseous product formed, when
An active metal reacts with dilute sulphuric acid.
What kind of a change is associated with decaying of a plants?
Write some materials prepared by chemical changes.
Which of the following are chemical changes?
(i) Decaying of wood
(ii) Burning of wood
(iii) Sawing of wood
(iv) Hammering of a nail into a piece of wood
Classify the following processes into physical or chemical changes:
- Beating of aluminium metal to make aluminium foil.
- Digestion of food.
- Cutting of a log of wood into pieces.
- Burning of crackers.
Heat may evolve or be absorbed during a ______ change.
What is thermochemical reactions?
What is the difference between reactants and products?
