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प्रश्न
Fill in the blank.
The formation of gas bubbles in a liquid during a reaction is called ......................
उत्तर
The formation of gas bubbles in a liquid during a reaction is called effervesence
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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.
Give one example that illustrates the following characteristics of a chemical reaction:
Change in state
Fill in the blanK
A .............is a substance which changes the rate of a chemical reaction without undergoing a chemical change.
Write the missing reactants and products and balance the equations.
\[\ce{KClO3 ->[heat]}\] ___________+ ____________
TRUE \ FALSE
Evaporation of water is a physical change. True or false ?
True or false
New substances are formed in a chemical change.
Fill in the blank
A new substance is formed in a _______ change.
Define chemical reaction.
Write true or false :
When potassium iodide solution is added to lead acetate solution a red precipitate is formed.
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)
Chlorine (Cl2) molecule is formed by ______ of electrons between two chlorine atoms.
Give an example of a reaction where the following are involved
Light
Give reason for the following:
Blue solution of copper sulphate changes to green when a piece of iron is added to this solution.
State the main characteristics of chemical reactions. Give at least one example in each case.
Define:
Electrochemical reaction
Give one example
Give a word equation for the following reaction.
Two gases which combine to give a solid.
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 dilute hydrochloric acid to silver nitrate.
Explain the term chemical reaction with special reference to reactants and products.
Give a suitable example with an equation to show the representation of a chemical reaction.
Name the solid residual product formed reaction and state its colour during – thermal decomposition of the following substance.
Zinc carbonate.
Name the solid residual product formed reaction and state its colour during – thermal decomposition of the following substance.
Lead nitrate.
The chemical change is ______.
Assertion: The formation of iron oxide from iron is a chemical change.
Reason: For the rust to form from iron, it must be exposed to air and water.
______ change results in the change of the substance.
Which of the following is a chemical change?
State whether the following statements are true or false:
When a candle burns, both physical and chemical changes take place.
Give two examples for each of the following cases:
Chemical changes.
A student took a solution of copper sulphate in a beaker and put a clean iron nail into it and left it for about an hour.
Write a word equation for the chemical change, if any.
The simplest method of preventing rusting of iron is to coat it with oil, grease, or paint. The reason being ______.
What is the difference between reactants and products?
What are the chemical reactions that occur in everyday life?
