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प्रश्न
Explain the following reaction with one suitable example of Combination reactions .
उत्तर
Combination reactions : In this reaction two or more substances combine to form a new substance, e.g. Burning of hydrogen in air.
APPEARS IN
संबंधित प्रश्न
Complete and balance the following chemical equations
NaCI + `AgNO_3` `→`
Give reason.
Wasp sting is treated with vinegar.
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 |
TRUE \ FALSE
Ammonia is a good oxidizing agent.
Balancing a chemical equation is based on
Copper carbonate when heated, it turns :
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)
Electron ______ is complete in each hydrogen in a hydrogen molecule.
Give an example of a reaction where the following are involved
Heat
Give an example of the following chemical change.
Two gases combine to form white solid
What do you observe? When
Water is added to the quick lime.
Name Affects the acidified K2Cr2O7 paper and also turns lime water dirty milky.
What do you observe when HCI is passed through a silver nitrate solution.
What do you observe when Cl2 is passed through potassium iodide (KI) solution.
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.
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.
Complete the table given below.
| Heat on copper carbonate | Test for gas evolved |
Select the correct answer from the options given below:
State the gaseous product formed, when
An ammonium salt reacts with an alkali.
______ gas causes tears in our eyes while cutting onions.
Burning of paper is a ______ change.
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?
Write some materials prepared by chemical changes.
Which of the following are chemical changes?
(i) Decaying of wood
(ii) Burning of wood
(iii) Sawing of wood
(iv) Hammering of a nail into a piece of wood
Give two examples for each of the following cases:
Chemical changes.
Vanaspati is obtained from vegetable oils by the addition of ______ to the oils.
The chemical name of baking soda is sodium bicarbonate.
Write the equation for the process of formation of rust.
______ is the chemical name of rust.
______ is a chemical substance is used in whitewashing.
