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Question
Fill in the blanK
A .............is a substance which changes the rate of a chemical reaction without undergoing a chemical change.
Solution
A catalyst is a substance which changes the rate of a chemical reaction without undergoing a chemical change.
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RELATED QUESTIONS
What are (i) positive catalysts and (ii) negative catalysts? Support your answer with one example for each of them.
Complete and balance the following chemical equations:
N2 + O2 →
Complete and balance the following chemical equations:
`"H"_2"S"` + `"CI"_2` `→`
Classify the following reaction as combination, decomposition, displacement, precipitation and neutralization. Also balance the equation.
\[\ce{NH3_{(g)} + HCl_{(g)} -> NH4Cl_{(s)}}\]
MULTIPLE CHOICE QUESTIONS
Tick the most appropriate answer.
Miscible liquids having slightly different boiling points can be separated by the
- evaporation
- distillation
- fractional distillation
- sedimentation
Fill in the blank
A new substance is always formed in a _______ change.
Fill in the blank:
The substances formed as a result of a chemical reaction are called _______
State what you would observe when the following substance is heated in a glass test tube 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)
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.
Limestone powder disappears on adding to dilute hydrochloric acids.
Give an example of a reaction where the following are involved
Light
Define Electrochemical reaction
Give an example
Write the chemical reaction where the following changes are observed.
Gas is evolved
Name: Two carbonates do not produce carbon dioxide on heating.
Give a chemical test to distinguish between the following gases.
H2 and CO2
Distinguish by heating the following in dry test tubs.
Zinc carbonate, Copper carbonate and lead carbonate.
Complete the table given below.
| Addition of dil. H2SO4 to FeS | Odour of gas evolved |
Burning of paper is a ______ change.
Limestone contains ______ mainly.
________ is a chemical substance which alters the speed of a chemical reaction.
Silver metal can displace hydrogen gas from nitric acid.
Match the following:
| 1. | Sodium Chloride | a. | CaSO41/2H2O |
| 2. | Calcium sulphate dihydrate | b. | C2H5Oh |
| 3. | Magnesium sulphate hydrate | c. | CaSO4.2H2O |
| 4. | Calcium sulphate hemihydrate | d. | NaCl |
| 5. | Phenol | e. | MgSO4.H2O |
Analogy:
H2O: Water:: NaCl: ______.
Classify each of the following, as a physical or a chemical change. Give reasons.
(a) Drying of a shirt in the sun.
(b) Rising of hot air over a radiator.
(c) Burning of kerosene in a lantern.
(d) Change the colour of black tea by adding lemon juice to it.
(e) Churning of milk cream to get butter.
State whether the following statements are true or false:
When a candle burns, both physical and chemical changes take place.
How can we prevent rusting?
Write a note on the following:
Fermentation
Acid rain is a result of ______.
Define the following term:
Chemical change
