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प्रश्न
How do the following help in bringing about a chemical change?
light.
उत्तर
Some chemical reactions can take place in the presence of light. Ex. Photosynthesis.
\[\ce{6CO2 + 6H2O⇌[sunlight][Chlorophyll]\underset{\text{glucose}}{C6H12O6 +6O2}}\]
APPEARS IN
संबंधित प्रश्न
The chemical name of baking soda is ______.
Write the missing reactants and products and balance the equations.
\[\ce{KClO3 ->[heat]}\] ___________+ ____________
What do you observe when Iron nail is kept in copper sulphate solution for sometime.
MULTIPLE CHOICE QUESTIONS
Tick the most appropriate answer.
Which one of the following alters the rate of the chemical reaction without itself undergoing any change?
- temperature and Pressure
- concentration of reactants
- presence of catalyst
- none of these
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 _______
Write true or false :
When iron and sulphur are heated together a grey mass is formed which is attracted by a magnet .
State what you would observe when the following substance is heated in a glass test tube red lead.
State what you would observe when the following substance is heated in a glass test tube Copper (II) carbonate Red lead .
| Reactants | Products | Type of chemical reaction |
| BaCl2(aq) + ZnSO4(aq) | H2CO3(aq) | Displacement |
| 2AgCl(s) | FeSO4(aq) + Cu(s) | Combination |
| CuSO4(aq) + Fe(s) | BaSO4↓ + ZnCl2(aq) | Decomposition |
| H2O(l) + CO2(g) | 2Ag(s) + Cl2(g) | Double displacement |
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)
Oxygen is a ______ in respiration.
Multiple choice:
A reaction of a type: AB + CD → AD + CD, involves
What do you understand by 'chemical reaction'?
Name the gases which Turn moist red litmus blue.
Give a chemical test to distinguish between the following gases.
H2 and O2
What do you observe when CO2 is passed through lime water first and then a little in excess.
Give a word equation for the following reaction.
Two gases which combine to give a solid.
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.
State the following reaction represent oxidation or reduction.
\[\ce{Al->Al+++}\]
Give two examples where a chemical reaction is accompanied by a change in colour of the reactants and products on completion of the reaction.
Give a balanced equation for a reaction involving the evolution of gas on the addition of dilute acid to calcium carbonate.
Name the solid residual product formed reaction and state its colour during – thermal decomposition of the following substance.
Copper nitrate.
Name the solid residual product formed reaction and state its colour during – thermal decomposition of the following substance.
Lead nitrate.
The chemical change is ______.
Which of the following statement is incorrect for a chemical reaction?
If you leave a piece of iron in the open for a few days, it acquires a film of brownish substance, called rust.
Can you change rust back into iron by some simple method?
When magnesium is burnt in the air, a new substance is formed which is ______.
Which is used as a catalyst during the process of hydrogenation of oils?
Write five changes in the characteristics of a substance that can take place during a chemical change.
Define the following term:
Chemical change
