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प्रश्न
What is a chemical reaction?
उत्तर
“Chemical reaction is a chemical change in which matter changes into a new substance or substances.”
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संबंधित प्रश्न
Complete and balance the following chemical equations
Na + H2 O →
Define precipitation.
TRUE \ FALSE
Copper can displace iron from iron sulphate.
Write a short note on the information derived from a balanced chemical equation.
Fill in the blank
A new substance is formed in a _______ change.
Explain the following reaction with one suitable example of Double decomposition 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)
A colourless solution of calcium hydroxide in a test tube turns ______ on blowing in it through a blow tube for some time.
Show with the help of diagram of electronic configuration how the following compound is formed from the constituent atoms.
Sodium chloride
Show with the help of diagram of electronic configuration how the following compound is formed from the constituent atoms.
Potassium fluoride
Choose the correct option from the bracket and explain the statement giving reason.
(Oxidation, displacement, electrolysis, reduction, zinc, copper, double displacement, decomposition)
The conversion of ferrous sulphate to ferric sulphate is ______ reaction.
Define Electrochemical reaction
Give an example
Give an example of the following chemical change.
Two gases combine to form white solid
What do you understand by precipitation reaction? Explain with examples.
Multiple choice:
Which of the following is not a characteristic of a chemical change?
State the original colour of the following substance and colour of residue obtained after heating.
Ammonium dichromate
Give a chemical test to distinguish between the following gases.
NH3 and SO2
What do you observe when dilute sulphuric acid is added to the following:
Sodium Sulphide
Select the correct answer for the following options:
The gas which reacts with oxygen to give a neutral liquid.
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.
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 – Thermal decomposition of mercury [II] oxide.
Photosynthesis is a chemical reaction that takes place in the presence of ______.
Silver metal can displace hydrogen gas from nitric acid.
Anaerobic bacteria digest animal waste and produce biogas (Change – A). The biogas is then burnt as fuel (Change – B). The following statements pertain to these changes. Choose the correct one.
The changes in which new substance with new chemical properties are formed are ______.
Chemical change is a temporary change.
______ change results in the change of the substance.
Burning of paper is the best example of ______ change.
Write word equations for two chemical reactions with the help of materials given in the box.
Air, copper sulphate, iron, vinegar, iron oxide, carbon dioxide, iron sulphate, copper, lime water, water
Give an example of a chemical reaction for each of the following situations:
A change in colour is observed.
Write five changes in the characteristics of a substance that can take place during a chemical change.
