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प्रश्न
Give reason for the following:
Electrolytic decomposition of water is a reaction involving change of state.
उत्तर
Electrolysis of water is the decomposition of water into hydrogen and oxygen due to the passage of electric current through it.
\[\ce{2H2O(l)->[Electric Current] 2H2 (g) + O2 (g)}\]
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संबंधित प्रश्न
When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain.
What do you observe when Iron nail is kept in copper sulphate solution for sometime.
MULTIPLE CHOICE QUESTIONS
Tick the most appropriate answer
Which of the following is a reducing agent?
- oxygen
- chlorine
- hydrogen
- none of these
FILL IN THE BLANK
Distillation is a method of obtaining pure ............. from a solution.
Explain the type of reactions on the basis of the direction of reaction.
What do you observe when :
an iron nail is kept in tap water for few days
Fill in the blank:
The substances which undergo chemical change are called _______
Write true or false :
Hydrogen sulphide has rotten egg smell .
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 white particles of baking soda disappear when put in lemon juice. This means that it is a ______ 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)
Electron ______ is complete in each hydrogen in a hydrogen molecule.
State the conditions necessary for a chemical change or reaction.
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.
Complete and balance the following reaction:
NaCl(aq) + AgNO3(aq) →
Name: A brown gas
What do you observe when Cobalt chloride paper is introduced in water vapour.
Give a chemical test to distinguish between the following gases.
SO2 and Cl2
Distinguish by heating the following in dry test tubs.
Zinc nitrate and copper nitrate.
Distinguish by dilute sulphuric acid.
Copper and magnesium?
Give reason for the following:
The catalytic oxidation of sulphur dioxide to sulphur trioxide is represented by a double arrow {⇌}
between the reactants and products, formed in the chemical reaction.
Name the following:
The type of change physical or chemical involved – ‘during respiration in human beings’.
Higher order Thinking question
Peeled and unpeeled banana does not look the same. Does that mean peeling banana is a chemical change?
When an aqueous solution of potassium chloride is added to an aqueous solution of silver nitrate, a white precipitate is formed. Give the chemical equation of this reaction.
Arrange the following statements in correct sequence:
- One side is water-loving and other water-hating molecules.
- When you agitate the cloth, the dirt is surrounded by many molecules and taken away from the cloth.
- The dirt surrounded by the detergent molecules floats in the water making it dirty.
- Finally, the cloth is clean.
- The detergent molecules have two sides.
- Water hating goes and joins with dirt and oil in the cloth while the water-loving joins with the water molecules.
Classify the following processes into physical or chemical changes:
(i) Beating of aluminium metal to make aluminium foil.
(ii) Digestion of food.
(iii) Cutting of a log of wood into pieces.
(iv) Burning of crackers.
Give an example of a chemical reaction for each of the following situations:
A change in colour is observed.
If you leave a piece of iron in the open for a few days, it acquires a film of brownish substance, called rust.
Can you change rust back into iron by some simple method?
______ occurs in the absence of air and in the presence of micro-organisms such as yeast.
______ is a chemical substance is used in whitewashing.
Write the effects of chemical reactions.
