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प्रश्न
State what you would observe when the following substance is heated in a glass test tube Copper (II) carbonate Red lead .
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उत्तर
CuCO3 → CuO + CO2 ↑
The blue-green powder turns black and a colourless gas is evolved which extinguishes a burning flame.
APPEARS IN
संबंधित प्रश्न
FILL IN THE BLANK
Negatively charged ions are called ..........
MATCH THE COLUMNS
| 1 . `H_2` + `CI_2` `→` 2HCI | a. displacement reaction |
| 2. `2FeCI_3`+ `H_2` `→` `2FeCI_2` +2HCI` | b. addition of an electronegative redical |
| 3. Fe + `CuSO_4` `→``FeSO_4` +Cu` | c. removal of an electronegative redical |
| 4. `2H_2O` +`4NO_2`+`O_2` `→` `4HNO_3` | d.reduction by adding hydrogen |
| 5. 3Fe +`3CI_2` `→` `2FeCI_3` | e.electrolysis of water |
| 6. `FeCI_3`+ 3NaOH `→``Fe(OH)_3``↓`+NaCI | F.double decomposition,precipitation reaction |
| 7.`2H_2O` `→` `2H_2``↑`+`O_2` | e. combination or synthesis reaction |
Fill in the blank:
During a chemical reaction transfer of ________ takes place.
Write true or false :
Hydrogen sulphide has rotten egg smell .
State four conditions necessary for a chemical reaction to take place.
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)
A colourless solution of calcium hydroxide in a test tube turns ______ on blowing in it through a blow tube for some time.
State the conditions necessary for a chemical change or reaction.
Give reason for the following:
Blue solution of copper sulphate changes to green when a piece of iron is added to this solution.
Multiple choice:
Which of the following is not a characteristic of a chemical change?
State the original colour of the following substance and colour of residue obtained after heating.
Ammonium dichromate
Give a chemical test to distinguish between the following gases.
H2 and CO2
Name the solid residual product formed reaction and state its colour during – thermal decomposition of the following substance.
Zinc carbonate.
______ gas causes tears in our eyes while cutting onions.
Which of the following is not an “element + element → compound” type reaction?
______ change results in the change of the substance.
The water we drink is a combination of hydrogen and oxygen.
Melting of wax is a change where a solid changes to liquid state. Give one more such change which you observe in your surroundings
If you leave a piece of iron in the open for a few days, it acquires a film of brownish substance, called rust.
Do you think formation of rust from iron is a chemical change?
Write the characteristics of chemical change.
What is the difference between reactants and products?
