Advertisements
Advertisements
प्रश्न
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 acid to an active metal.
Advertisements
उत्तर
Addition of dil. acid to an active metal: Gas is evolved, test tube or flask becomes hot (heat is produced).
APPEARS IN
संबंधित प्रश्न
How do the following help in bringing about a chemical change?
heat.
MULTIPLE CHOICE QUESTIONS
Tick the most appropriate answer.
Which one of the following alters the rate of the chemical reaction without itself undergoing any change?
- temperature and Pressure
- concentration of reactants
- presence of catalyst
- none of these
What are biocatalysts ?
Name three reducing agents ?
Differentiate between in Chemical reaction and chemical equation.
Write true or false :
Hydrogen sulphide has rotten egg smell .
Write true or false :
When potassium iodide solution is added to lead acetate solution a red precipitate is formed.
Write balanced chemical equations for the reactions represented by word equations in the conditions for chemical reaction.
Name the type of chemical reaction shown by the following equation:
CaCO3 → CaO + CO2
Out of sodium and sulphur which is a metal? Explain its reaction with the oxygen.
Explain by writing a word equation.
Respiration is a chemical change.
Give reason for the following:
Silver nitrate solution is kept in coloured bottles.
What do you observe? When
Barium chloride is added to sodium sulphate solution
Give a word equation for the following reaction.
Two gases which combine to give a solid.
Give reason for the following:
Electrolytic decomposition of water is a reaction involving change of state.
Name the following:
The products obtained during ‘photosynthesis’ – which is a chemical change.
Give balanced equation for the following conversion affected by heat alone on the substance:
Zinc carbonate to zinc oxide
Give two examples for the following case:
Chemical changes
______ are substances that speed up the process of a chemical change and it will not undergo any change during the course of the reaction.
We are advised to not to play with fireworks. Give reason.
