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प्रश्न
Write true or false :
When iron and sulphur are heated together a grey mass is formed which is attracted by a magnet .
विकल्प
True
False
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उत्तर
False
APPEARS IN
संबंधित प्रश्न
Complete and balance the following chemical equations:
Zn + `"H"_2"SO"_4` `→`
(dil)
Write the missing reactants and products and balance the equations.
................+ HCI `→` NaCI + `"H"_2"O"` + .........................
FILL IN THE BLANK
Negatively charged ions are called ..........
Fill in the blank
A change in which the substance can be brought back to its original state is called a _______ change.
Fill in the blank:
The substances which undergo chemical change are called _______
Fill in the blank:
During a chemical reaction transfer of ________ takes place.
Name the type of chemical reaction shown by the following equation :
Fe2O3 + 2Al → Al2O3 + 2Fe
Complete the statement by filling the gaps using appropriate term from the terms given in the bracket.
(slow, coloured, arrow, fast, smell, milky, physical, product, chemical, reactant, covalent, ionic, octet, duplet, exchange, sharing, equality sign)
The white particles of baking soda disappear when put in lemon juice. This means that it is a ______ change.
Explain by writing a word equation.
Respiration is a chemical change.
Give an example of a reaction where the following are involved
Catalyst
Write the chemical reaction where the following changes are observed.
Physical state is changed
Write your observation and a balanced equation in the case of the following substances being heated.
Ammonium chloride
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.
Complete the table given below.
| Heat on sodium chloride | Colour imparted to flame during flame test |
Give two examples where a chemical reaction is accompanied by a change in colour of the reactants and products on completion of the reaction.
______ gas causes tears in our eyes while cutting onions.
Assertion: The formation of iron oxide from iron is a chemical change.
Reason: For the rust to form from iron, it must be exposed to air and water.
Write a note on the catalyst.
Chemical changes are important in our day-to-day life. Give examples.
Assertion (A): Cutting paper into very small pieces is an irreversible change.
Reason (R): Physical changes are always reversible.
