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.
संबंधित प्रश्न
How do the following help in bringing about a chemical change?
catalyst .
Complete and balance the following chemical equations:
Ba`"CI"_2` + `"H"_2"SO"_4` `→`
(aq.) (aq.)
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
Weak electrolytes dissociate partially in their aqueous or fused state.
TRUE \ FALSE
Electrolytic refining is a method in which a thin coating of a metal is done over another metal.
What are chemical reactions?
State four conditions necessary for chemical reactions to take place.
Out of sodium and sulphur which is a metal? Explain its reaction with the oxygen.
State the conditions necessary for a chemical change or reaction.
Define an electrochemical reaction.
What do you understand by precipitation reaction? Explain with examples.
State the original colour of the following substance and colour of residue obtained after heating.
Zinc carbonate
What do you observe when CO2 is passed through lime water first and then a little in excess.
Give reason for the following:
A characteristic change of colour is seen when a piece of iron is added to copper [II] sulphate solution.
Give balanced equation for the following conversion affected by heat alone on the substance:
Copper carbonate to copper oxide
Name the solid residual product formed reaction and state its colour during – thermal decomposition of the following substance.
Ammonium dichromate.
Explain the following statement: Digestion is a chemical change.
A reaction between an acid and a base is called ______.
If you leave a piece of iron in the open for a few days, it acquires a film of brownish substance, called rust.
Can you change rust back into iron by some simple method?
When milk is mixed with coffee decoction, the colour of milk and decoction changes due to ______.
