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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.
उत्तर
A catalyst is a substance which changes the rate of a chemical reaction without undergoing a chemical change.
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संबंधित प्रश्न
How would you show that setting of curd is a chemical change?
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
The new substances formed during a chemical reaction are called the ..................
TRUE \ FALSE
Positively charged electrode is called the anode. True or false ?
Explain the type of reactions on the basis of the direction of reaction.
A solution of a substance ‘X’ is used for white washing write the reaction of the substance ‘X’ named in (a) above with water.
Explain by writing a word equation.
Hard water gets softened on mixing with a solution of washing soda.
Give an example of a reaction where the following are involved
Catalyst
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
What do you observe when Cobalt chloride paper is introduced in water vapour.
Distinguish by heating the following in dry test tubs.
Copper Sulphate and copper carbonate
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.
A salt which reacts with ammonium hydroxide to give a reddish brown precipitate.
Give balanced equation for the following conversion affected by heat alone on the substance:
Zinc nitrate to nitrogen dioxide
Complete the table given below.
| Heat on Zinc nitrate | Colour of residue |
State the following reaction represent oxidation or reduction.
\[\ce{Cu++->Cu}\]
State the following reaction represent oxidation or reduction.
\[\ce{H->H+}\]
Give a balanced equation for the conversion of a soluble lead salt to an insoluble lead salt – formed as a white precipitate.
Complete the statement by filling in the blank with the correct word:
The reddish-brown precipitate obtained during a double decomposition precipitation reaction between an iron salt and alkali is __________.
Circle the odd one out. Give reason for your choice
NPK are the primary nutrients for plants.
A thick coating of a paste of Plaster of Paris (POP) is applied over the bandage on a fractured bone. It becomes hard on drying to keep the fractured bone immobilised. Can the change in POP be reversed?
Silver articles turning black: ______:: Boiling of H2O: physical change ______.
Is the conversion of milk into ice cream a chemical change?
Which is used as a catalyst during the process of hydrogenation of oils?
Assertion (A): Cutting paper into very small pieces is an irreversible change.
Reason (R): Physical changes are always reversible.
What is thermochemical reactions?
