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प्रश्न
Fill in the blank
A new substance is formed in a _______ change.
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उत्तर
A new substance is formed in a chemical change.
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संबंधित प्रश्न
Complete and balance the following chemical equations:
N2 + O2 →
Fill in the blank
A catalyst either ................or ............... the rate of a chemical change but itself remains ............... at the end of the reaction.
Write the missing reactants and products and balance the equations.
\[\ce{KClO3 ->[heat]}\] ___________+ ____________
True or false
New substances are formed in a chemical change.
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 spoiling of food is a chemical change which is recognized from the generation of certain ______ due to it.
Explain the term reactant and product giving examples.
Give an example of a reaction where the following are involved
Electricity
Give an example of a reaction where the following are involved:
Close contact
Give an example of the following chemical changes.
A reaction involving
(i) Change of state
(ii) formation of precipitate
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.
Lead nitrate
Give a word equation for the following reaction.
Two solids which combine on heating, to give a liquid.
A chemical reaction is often accompanied by external indications or characteristics which include –
- Colour change
- Effervescence or gas evolved
- Evolution or absorption of heat
- Formation of a precipitate.
With reference to each of the above indications, state the external indication seen during – Addition of water to quicklime.
Complete the table given below.
| Heat on sodium chloride | Colour imparted to flame during flame test |
Complete the table given below.
| Flame test for calcium chloride | Acid used for flame test |
Classify the following as physical or chemical properties
Zinc dissolves in hydrochloric acid with the evolution of hydrogen gas.
Magnesium + oxygen → magnesium oxide.
2Mg + O2 → 2Mg O
How can we prevent rusting?
Write a note on the following:
Curdling of milk
______ is the chemical name of slaked lime.
