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.
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
Complete and balance the following chemical equations:
N2 + O2 →
Complete and balance the following chemical equations:
Zn + `"H"_2"SO"_4` `→`
(dil)
Give reason .
A person suffering from acidity is advised to take an antacid.
FILL IN THE BLANK
A .............. change is a temporary change.
Is kerosene an electrolyte or a non-electrolyte ?
Write a short note on the information derived from a balanced chemical equation.
A chemical equation is a statement that describes a chemical change in terms of
Show with the help of diagram of electronic configuration how the following compound is formed from the constituent atoms.
Water
Give an example of a reaction where the following are involved
Catalyst
Give reason for the following:
Blue solution of copper sulphate changes to green when a piece of iron is added to this solution.
Complete and balance the following reaction:
\[\ce{CuCO3 ->[\Delta]}\]
What do you observe when Cobalt chloride paper is introduced in water vapour.
Give a chemical test to distinguish between the following gases.
HCl and H2S
What do you observe when dilute sulphuric acid is added to the following:
Sodium Sulphide
Distinguish by heating the following in dry test tubs.
Copper Sulphate and copper carbonate
Give a word equation for the following reaction.
A salt which reacts with ammonium hydroxide to give a reddish brown precipitate.
On heating which of the following substances i.e. copper carbonate, zinc carbonate, washing soda, copper sulphate, zinc nitrate, copper nitrate, lead nitrate, ammonium chloride and ammonium dichromate – relate to the reaction given below.
A coloured substance which leaves on strong heating a black residue and evolves two colourless gases one of which is acidic and the other neutral.
Give balanced equation for the following conversion affected by heat alone on the substance:
Hydrated copper sulphate to sulphur dioxide
Complete the table given below.
| Heat on ammonium dichromate | Name of neutral gas evolved |
State the following reaction represent oxidation or reduction.
\[\ce{Fe++->Fe+++}\]
Give a balanced equation for the conversion of a soluble lead salt to an insoluble lead salt – formed as a white precipitate.
Mention the various conditions required for a chemical reaction to occur.
Water boiling into water vapour is an example of chemical change.
______ is a natural indicator.
A chemical change may involve –
How would you show that the settling of curd is a chemical change?
______ is the chemical name of slaked lime.
What is thermochemical reactions?
