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प्रश्न
Give a reason.
Wasp sting is treated with vinegar.
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उत्तर
Wasp stings are alkaline and they can be neutralized by vinegar which is a weak acid.
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संबंधित प्रश्न
Fill in the blank
A catalyst either ................or ............... the rate of a chemical change but itself remains ............... at the end of the reaction.
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 ?
What do you observe when :
an iron nail is kept in tap water for few days
Differentiate between in Chemical reaction and chemical equation.
Write true or false :
No new substance is formed during a chemical reaction.
Balancing a chemical equation is based on
Explain the following reaction with one suitable example of Decomposition reaction
Complete the following table and write your observations.
|
Hydrogen sulphide |
Ammonia |
Sulphur dioxide |
Hydrogen chloride |
|
|
Shake the gas with red litmus solution |
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Shake the gas with blue litmus solution |
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|
Apply a burning splint to a gas |
Explain the term ‘chemical reaction’ with special reference to – ‘reactants’ and ‘products’.
Give examples of exothermic reactions i.e. heat evolved in each of the following:
(a) reaction between a solid and a liquid
(b) reaction between two gases
Give two examples of exothermic reactions seen in everyday life.
Complete the table given below.
| Addition of dil. H2SO4 to KHCO3 | Name of residue obtained |
Give a balanced equation for the conversion of a soluble lead salt to an insoluble lead salt – formed as a white precipitate.
Name the solid residual product formed reaction and state its colour during – thermal decomposition of the following substance.
Copper nitrate.
Name the solid residual product formed reaction and state its colour during – thermal decomposition of the following substance.
Ammonium dichromate.
Water boiling into water vapour is an example of chemical change.
Two chemical species X and Y combine together to form a product P which contains both X and Y
\[\ce{X + Y -> P}\]
X and Y cannot be broken down into simpler substances by simple chemical reactions. Which of the following concerning the species X, Y and P are correct?
(i) P is a compound
(ii) X and Y are compounds
(iii) X and Y are elements
(iv) P has a fixed composition
Beating an egg to make a cake is a ______.
Write a note on the following:
Fermentation
