Advertisements
Advertisements
प्रश्न
State the original colour of the following substance and colour of residue obtained after heating.
Ammonium dichromate
उत्तर
Ammonium dichromate is a bright orange-red crystalline solid. It is readily ignited and burns to produce a voluminous green residue.
APPEARS IN
संबंधित प्रश्न
Complete and balance the following chemical equations:
Zn + `"H"_2"SO"_4` `→`
(dil)
Complete and balance the following chemical equations:
Ba`"CI"_2` + `"H"_2"SO"_4` `→`
(aq.) (aq.)
Write balanced chemical equations for the reactions represented by word equations in the conditions for chemical reaction.
Give an example of a reaction where the following are involved:
Close contact
Give an example of a reaction where the following are involved
Catalyst
Give an example of the following chemical change.
Two gases combine to form white solid
Distinguish by heating the following in dry test tubs.
Zinc nitrate and copper nitrate.
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 water to quicklime.
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 white solid which evolves two colourless gases which on cooling combine and condense on the cooler parts of the test tube.
A bag of cement lying in the open gets wet due to rain during the night. The next day the sun shines brightly. Do you think the changes, which have occurred in the cement, could be reversed?
The changes in which new substance with new chemical properties are formed are ______.
______ change results in the change of the substance.
Chemists identify gypsum as a natural indicator.
Write some materials prepared by chemical changes.
Give an example of a chemical reaction for each of the following situations:
A change in colour is observed.
Iron and rust are the same substances.
Both CO2 and H2 gases are ______.
______ is the chemical name of rust.
Define the following term:
Chemical change
