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प्रश्न
Fill in the blanK
A .............is a substance which changes the rate of a chemical reaction without undergoing a chemical change.
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उत्तर
A catalyst is a substance which changes the rate of a chemical reaction without undergoing a chemical change.
APPEARS IN
संबंधित प्रश्न
State whether the following statement is true or false. In case a statement is false, write the corrected statement.
Condensation of steam is not a chemical change.
How do the following help in bringing about a chemical change?
light.
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
TRUE \ FALSE
Temperature at which a liquid starts boiling is known as the boiling point of that liquid. True or false ?
Choose the correct option from the bracket and explain the statement giving reason.
(Oxidation, displacement, electrolysis, reduction, zinc, copper, double displacement, decomposition)
To prevent rusting, a layer of ______ metal is applied on iron sheets.
Define a photochemical reaction.
Give reason for the following:
Molybdenum is used in the manufacture of ammonia.
Give an example of a photochemical reaction.
State the original colour of the following substance and colour of residue obtained after heating.
Copper carbonate
Give a chemical test to distinguish between the following gases.
NH3 and SO2
Give balanced equation for the following conversion affected by heat alone on the substance:
Zinc nitrate to nitrogen dioxide
Give a suitable example with an equation to show the representation of a chemical reaction.
Give a balanced equation for a reaction involving the evolution of gas on the addition of dilute acid to sodium sulphite.
Give a balanced equation for the conversion of an ammonium salt to a basic gas.
Explain with the help of balanced equations, how precipitation reactions are used for identifying the positive radicals in three different salts, each having a different cation [positive ion].
Silver articles turning black: ______:: Boiling of H2O: physical change ______.
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.
Which of the following statement is incorrect for a chemical reaction?
The chemical name of baking soda is sodium bicarbonate.
Why is spoiling food a chemical change?
