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प्रश्न
State what you would observe when the following substance is heated in a glass test tube red lead.
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उत्तर
2Pb3O4 → 6PbO + O2 ↑
The dark red lead as red powder changes to yellow colour. The yellow colour residue on further heating sticks to the tube and give reddish colour to glass. A colourless and odourless gas is evolved.
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संबंधित प्रश्न
Complete and balance the following chemical equations:
Ba`"CI"_2` + `"H"_2"SO"_4` `→`
(aq.) (aq.)
MULTIPLE CHOICE QUESTIONS
Tick the most appropriate answer
Which of the following is a reducing agent?
- oxygen
- chlorine
- hydrogen
- none of these
TRUE \ FALSE
Temperature at which a liquid starts boiling is known as the boiling point of that liquid. True or false ?
Name three reducing agents ?
Define chemical reaction.
Complete the statement by filling the gap using an 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)
An ______ is drawn in between the reactants and products while writing the equation for a chemical reaction.
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)
The spoiling of food is a chemical change which is recognized from the generation of certain ______ due to it.
Write the chemical reaction where the following changes are observed.
Physical state is changed
Give an example of the following chemical changes.
A reaction involving
(i) Change of state
(ii) formation of precipitate
Name: Gas with rotten egg smell.
State the original colour of the following substance and colour of residue obtained after heating.
Copper carbonate
Distinguish by heating the following in dry test tubs.
Ammonium Chloride and iodine.
Give balanced equation for the following conversion affected by heat alone on the substance:
Copper carbonate to copper oxide
Give a balanced equation for a reaction involving the evolution of gas on the addition of dilute acid to sodium sulphite.
Assertion: The formation of iron oxide from iron is a chemical change.
Reason: For the rust to form from iron, it must be exposed to air and water.
Write some materials prepared by chemical changes.
On heating calcium carbonate gets converted into calcium oxide and carbon dioxide.
(a) Is this a physical or a chemical change?
(b) Can you prepare one acidic and one basic solution by using the products formed in the above process? If so, write the chemical equation involved.
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.
Write five changes in the characteristics of a substance that can take place during a chemical change.
Write the effects of chemical reactions.
