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प्रश्न
Fill in the blank.
Melting of ice is a _______ change.
उत्तर
Melting of ice is a physical change.
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संबंधित प्रश्न
Complete and balance the following chemical equations:
\[\ce{Pb(NO3)2->[heat]}\] _________
Fill in the blank
A catalyst either ................or ............... the rate of a chemical change but itself remains ............... at the end of the reaction.
Give reason .
A person suffering from acidity is advised to take an antacid.
FILL IN THE BLANK
On reaction with sulphuric acid solution, barium chloride forms a white precipitate of ........ sulphate.
FILL IN THE BLANK
The new substances formed during a chemical reaction are called the ..................
TRUE \ FALSE
The evolution of a gas during a chemical reaction is shown by an arrow pointing downwards. True or false ?
How is a strong electrolyte different from a weak electrolyte?
Write true or false :
No new substance is formed during a chemical reaction.
Balancing a chemical equation is based on
Define Electrochemical reaction
Give an example
Write the chemical reaction where the following changes are observed.
Colour change is noticed
Give reason for the following:
Colourless concentrated sulphuric acid in a test tube changes to blue on adding a small piece of copper to it.
What do you understand by 'chemical reaction'?
Name Affects the acidified K2Cr2O7 paper and also turns lime water dirty milky.
State the original colour of the following substance and colour of residue obtained after heating.
Ammonium dichromate
Give a chemical test to distinguish between the following gases.
HCl and H2S
Give a word equation for the following reaction.
Two solids which combine on heating, to give a liquid.
Name the following:
The products obtained during ‘photosynthesis’ – which is a chemical change.
What is a chemical reaction?
Give balanced equation for the following conversion affected by heat alone on the substance:
Zinc carbonate to zinc oxide
Complete the table given below.
| Addition of dil. H2SO4 to zinc | Test for gas evolved |
Give a suitable example with an equation to show the representation of a chemical reaction.
A chemical reaction is often accompanied by external indications or characteristics.
Give two examples where a chemical reaction is accompanied by a change in colour of the reactants and products on completion of the reaction.
Select the correct answer from the options given below:
State the gaseous product formed, when
An ammonium salt reacts with an alkali.
Circle the odd one out. Give reason for your choice
The water we drink is a combination of hydrogen and oxygen.
Rusting of iron is ______.
The chemical formula of rust is ______.
When milk is mixed with coffee decoction, the colour of milk and decoction changes due to ______.
