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प्रश्न
What is a chemical reaction?
उत्तर
A chemical reaction is the process of breaking the chemical bonds of the reacting substances (reactants) and making new bonds to form new substances (products).
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संबंधित प्रश्न
How do the following help in bringing about a chemical change?
heat.
What are (i) positive catalysts and (ii) negative catalysts? Support your answer with one example for each of them.
Define catalyst.
FILL IN THE BLANK
Negatively charged ions are called ..........
FILL IN THE BLANK
In a ............ change, new substances are formed.
State four conditions necessary for chemical reactions to take place.
Write true or false :
Hydrogen sulphide has rotten egg smell .
| Reactants | Products | Type of chemical reaction |
| BaCl2(aq) + ZnSO4(aq) | H2CO3(aq) | Displacement |
| 2AgCl(s) | FeSO4(aq) + Cu(s) | Combination |
| CuSO4(aq) + Fe(s) | BaSO4↓ + ZnCl2(aq) | Decomposition |
| H2O(l) + CO2(g) | 2Ag(s) + Cl2(g) | Double displacement |
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.
Hydrogen chloride
Give an example of a reaction where the following are involved
Pressure
What is a chemical change? Give two examples of chemical change?
State the main characteristics of chemical reactions. Give at least one example in each case.
Select the correct answer for the following options:
The gas obtained when potassium chlorate is heated in the presence of a catalyst.
Burning of paper is the best example of ______ change.
A student took a solution of copper sulphate in a beaker and put a clean iron nail into it and left it for about an hour.
What changes do you expect?
A student took a solution of copper sulphate in a beaker and put a clean iron nail into it and left it for about an hour.
Write a word equation for the chemical change, if any.
Write the equation for the process of formation of rust.
Write a note on the catalyst.
Assertion (A): Cutting paper into very small pieces is an irreversible change.
Reason (R): Physical changes are always reversible.
