Advertisements
Advertisements
प्रश्न
Define catalyst.
Advertisements
उत्तर
A catalyst is a substance that either increases or decreases the rate of a chemical reaction without itself undergoing any chemical change during the reaction.
APPEARS IN
संबंधित प्रश्न
How do the following help in bringing about a chemical change?
heat.
Complete and balance the following chemical equations
Na + H2 O →
Fill in the blank
A catalyst either ................or ............... the rate of a chemical change but itself remains ............... at the end of the reaction.
Give a reason.
Wasp sting is treated with vinegar.
Explain the term reactant and product giving examples.
Define the following term:
Precipitate
Complete and balance the following reaction:
\[\ce{CuCO3 ->[\Delta]}\]
Give a chemical test to distinguish between the following gases.
H2 and CO2
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 iodine crystals | Colour of vapours evolved |
Explain the Silver nitrate solution is kept in coloured reagent bottles in the laboratory.
Name the solid residual product formed reaction and state its colour during – thermal decomposition of the following substance.
Lead nitrate.
True or False. If false, give the correct answer.
Taking a glass of water and freezing it by placing it in the freezer is a chemical change.
________ is a chemical substance which alters the speed of a chemical reaction.
The percentage composition of Nitrogen in Ureas is ______.
Chemists identify gypsum as a natural indicator.
What is the use of indicator?
State whether the following statement is true or false:
When a candle burns, both physical and chemical changes take place.
Beating an egg to make a cake is a ______.
Define the following term:
Chemical change
