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प्रश्न
Explain the following reaction with one suitable example of Decomposition reaction
उत्तर
Decomposition reaction : In this reaction a substance breaks up on heating to form two or more simpler substances, e.g. Electrolysis of water.
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संबंधित प्रश्न
Define; catalyst.
Complete and balance the following chemical equations:
Zn + `"H"_2"SO"_4` `→`
(dil)
Complete and balance the following chemical equations:
Fe `"SO"_4` + NaOH `→`
(aq.) (aq.)
Write the missing reactants and products and balance the equations.
\[\ce{KClO3 ->[heat]}\] ___________+ ____________
Give reason.
Wasp sting is treated with vinegar.
MULTIPLE CHOICE QUESTIONS
Tick the most appropriate answer.
Miscible liquids having slightly different boiling points can be separated by the
- evaporation
- distillation
- fractional distillation
- sedimentation
FILL IN THE BLANK
Positively charged ions are called ........
TRUE \ FALSE
Temperature at which a liquid starts boiling is known as the boiling point of that liquid. True or false ?
A chemical equation is a statement that describes a chemical change in terms of
Balancing a chemical equation is based on
A solution of a substance ‘X’ is used for white washing Name the substance ‘X’ and write its formula.
A solution of a substance ‘X’ is used for white washing write the reaction of the substance ‘X’ named in (a) above with water.
Choose the correct option from the bracket and explain the statement giving reason.
(Oxidation, displacement, electrolysis, reduction, zinc, copper, double displacement, decomposition)
To prevent rusting, a layer of ______ metal is applied on iron sheets.
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)
A colourless solution of calcium hydroxide in a test tube turns ______ on blowing in it through a blow tube for some time.
What do you understand by 'chemical reaction'?
Give an example of the following chemical changes.
A reaction involving
(i) Change of state
(ii) formation of precipitate
Distinguish by heating the following in dry test tubs.
Zinc nitrate and copper nitrate.
What is a chemical reaction?
A chemical reaction is often accompanied by external indications or characteristics which include –
- Colour change
- Effervescence or gas evolved
- Evolution or absorption of heat
- Formation of a precipitate.
With reference to each of the above indications, state the external indication seen during – Addition of dilute hydrochloric acid to silver nitrate.
Give balanced equation for the following conversion affected by heat alone on the substance:
Zinc carbonate to zinc oxide
Give balanced equation for the following conversion affected by heat alone on the substance:
Zinc nitrate to nitrogen dioxide
Give two examples where a chemical reaction is accompanied by a change in colour of the reactants and products on completion of the reaction.
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.
Burning of paper is the best example of ______ change.
Beating an egg to make a cake is a ______.
Explain how the painting of an iron gate prevents it from rusting.
Chemical changes are important in our day-to-day life. Give examples.
______ is the chemical name of slaked lime.
Collect information about the types of fuels used for cooking in your area. Discuss with your teachers/parents/others which fuels are less polluting and why.
