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प्रश्न
Fill in the blank
A catalyst either ................or ............... the rate of a chemical change but itself remains ............... at the end of the reaction.
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उत्तर
A catalyst either increases or decreases the rate of a chemical change but itself remains unchanged at the end of the reaction.
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संबंधित प्रश्न
Fill in the blank:
The substances formed as a result of a chemical reaction are called _______
Fill in the blank:
The basic conditions necessary for a chemical reaction is _______
Match the column in the following table.
| 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 |
Write the chemical reaction where the following changes are observed.
Precipitate is formed
Multiple choice:
A reaction of a type: AB + CD → AD + CD, involves
Complete and balance the following reaction:
\[\ce{CuCO3 ->[\Delta]}\]
Complete and balance the following reaction:
\[\ce{NH3 + O2 ->[\Delta]}\]
What is observed in performing the following :
| Hydrogen | Oxygen | Carbon dioxide | Chlorine | |
| Litmus test | ||||
| Apply a burning splint to the gas | ||||
| Colour of gas | colourless | colourless | colourless | greenish-yellow |
| Odour of gas |
Explain the term ‘chemical reaction’ with special reference to – ‘reactants’ and ‘products’.
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.
Complete the table given below.
| Heat on copper carbonate | Test for gas evolved |
State the following reaction represent oxidation or reduction.
\[\ce{Al->Al+++}\]
______ gas causes tears in our eyes while cutting onions.
Higher order Thinking question
A very hot glass on putting in cold water cracks. What does this change indicate?
________ is a chemical substance which alters the speed of a chemical reaction.
Silver articles turning black: ______:: Boiling of H2O: physical change ______.
The percentage composition of Nitrogen in Ureas is ______.
State whether the following statement is true or false:
When a candle burns, both physical and chemical changes take place.
The chemical formula of rust is ______.
What is the difference between reactants and products?
