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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
Name three biochemical catalysts found in the human body.
Complete and balance the following chemical equations:
N2 + O2 →
Write the missing reactants and products and balance the equations.
................+ HCI `→` NaCI + `"H"_2"O"` + .........................
How is precipitate formation in a chemical reaction indicated?
True or false
New substances are formed in a chemical change.
Match the pairs.
| a. | Photosynthesis | i. | Tendency to lose electrons |
| b. | Water | ii. | Reactant in combustion process |
| c. | Sodium chloride | iii. | Chemical change |
| d. | Dissolution of salt in water | iv. | Covalent bond |
| e. | Carbon | v. | Ionic bond |
| f. | Fluorine | vi. | Physical change |
| g. | Magnesium | vii. | Tendency to form anion |
Give an example of a reaction where the following are involved:
Close contact
Complete the following table and write your observations.
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Hydrogen sulphide |
Ammonia |
Sulphur dioxide |
Hydrogen chloride |
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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 |
Distinguish by dilute sulphuric acid.
Sodium Sulphite and sodium carbonate?
Complete the table given below.
| Heat on Zinc nitrate | Colour of residue |
Complete the table given below.
| Addition of dil. H2SO4 to KHCO3 | Name of residue obtained |
Complete the table given below.
| Heat on sodium chloride | Colour imparted to flame during flame test |
Complete the statement by filling in the blank with the correct word:
The reddish-brown precipitate obtained during a double decomposition precipitation reaction between an iron salt and alkali is __________.
______ gas causes tears in our eyes while cutting onions.
Which of the following is/are true when milk changes into curd?
- Its state is changed from liquid to semi solid.
- It changes colour.
- It changes taste.
- The change cannot be reversed.
Choose the correct option from below:
______ occurs in the absence of air and in the presence of micro-organisms such as yeast.
______ is the chemical name of rust.
What is thermochemical reactions?
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.
