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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
Fill in the blank.
The formation of gas bubbles in a liquid during a reaction is called ......................
FILL IN THE BLANK
The new substances formed during a chemical reaction are called the ..................
What are chemical reactions?
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)
A colourless solution of calcium hydroxide in a test tube turns ______ on blowing in it through a blow tube for some time.
When electric current is passed through acidulated water ______ of water takes place.
Give an example of a reaction where the following are involved
Light
Explain,giving one example of the following chemical changes:
Reversible reaction
What do you observe? When
Sodium chloride solution is added to silver nitrate solution.
Give a chemical test to distinguish between the following gases.
NH3 and SO2
What do you observe when dilute sulphuric acid is added to the following:
Sodium Sulphide
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.
A chemical reaction is often accompanied by external indications or characteristics.
Discuss how acid rain occurs due to emission of smoke from vehicles and industries?
Which of the following is not an “element + element → compound” type reaction?
Chemical change is a temporary change.
The water we drink is a combination of hydrogen and oxygen.
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.
The chemical name of baking soda is sodium bicarbonate.
Chemical changes are important in our day-to-day life. Give examples.
Assertion (A): Cutting paper into very small pieces is an irreversible change.
Reason (R): Physical changes are always reversible.
