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प्रश्न
How do the following help in bringing about a chemical change?
catalyst .
उत्तर
A catalyst can either increases or decreases the rate of chemical reaction and some chemical reactions need a catalyst to change the rate of the reaction, in case it is too slow or too fast
1. Positive catalyst: When a catalyst increase the rate of reaction finely divided iron is used as a positive catalyst in the manufacturing of ammonia from hydrogen and nitrogen.
\[\ce{N2 + 3H2 ⇌[Iron (Catalyst) 200-900][450°C] 2NH3 + Heat}\]
2. Negative Catalyst: When a catalyst decreases the rate of reaction.
Ex. Phosphoric acid act as a negative catalyst to decrease the rate of the decomposition of hydrogen peroxide.
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संबंधित प्रश्न
Complete and balance the following chemical equations:
Zn + `"H"_2"SO"_4` `→`
(dil)
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\[\ce{NH3_{(g)} + HCl_{(g)} -> NH4Cl_{(s)}}\]
Write the missing reactants and products and balance the equations.
\[\ce{KClO3 ->[heat]}\] ___________+ ____________
Write true or false :
When iron and sulphur are heated together a grey mass is formed which is attracted by a magnet .
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State what you would observe when the following substance is heated in a glass test tube Copper (II) carbonate Red lead .
Name the type of chemical reaction shown by the following equation :
Fe2O3 + 2Al → Al2O3 + 2Fe
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Complete the statement by filling the gaps using appropriate term from the terms given in the bracket.
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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 the following chemical changes.
A reaction involving
(i) Change of state
(ii) formation of precipitate
Complete and balance the following reaction:
NaCl(aq) + AgNO3(aq) →
Complete and balance the following reaction:
\[\ce{Pb(NO3)2 ->[\Delta]}\]
Complete and balance the following reaction:
\[\ce{NH3 + O2 ->[\Delta]}\]
Give a chemical test to distinguish between the following gases.
NH3 and HCl
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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.
| Addition of dil. H2SO4 to zinc | Test for gas evolved |
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 __________.
Select the correct answer from the options given below:
State the gaseous product formed, when
An ammonium salt reacts with an alkali.
What kind of a change is associated with decaying of a plants?
Higher order Thinking question
Peeled and unpeeled banana does not look the same. Does that mean peeling banana is a chemical change?
Can a nickel spatula be used to stir copper sulphate solution? Justify your answer.
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?
Chemical change is a temporary change.
The percentage composition of Nitrogen in Ureas is ______.
Burning of paper is the best example of ______ change.
Write the characteristics of chemical change.
______ is the chemical name of rust.
