This lesson is one of the most important lessons for the NIOS Class 10 Science examination. Questions are frequently asked on balancing equations, types of reactions, corrosion, rancidity, diagrams and case study-based questions.
This post covers
all important questions with exam ready answers as per NIOS pattern.
MCQs with
Answers
Q1. A chemical equation is a :
(a) Statement
(b) Symbolic representation
(c) Diagram
(d) Formula
Correct answer - (b) Symbolic representation
Q2. A balanced equation follows:
(a) Ohm’s law
(b) Boyle’s law
(c) Law of conservation of mass
(d) Low of constant proportion
Correct answer - (c) Law of conservation of mass
Q3. Mg + O2 →MgO is:
(a) Balanced
(b) Skeletal
(c) Word
(d) Ionic
Correct answer - (b) Skeletal
Q4. Which method is commonly used to balance a chemical equation?
(a) Substitution method
(b) Hit and trail method
(c) Cross multiplication method
(d) Elimination method
Correct answer - (b) Hit and trail method
Q5. The reaction CaO + H2O →Ca(OH)2
(a) Decomposition reaction
(b) Displacement reaction
(c) Combination reaction
(d) Double displacement reaction
Correct answer- (c) Combination reaction
Q6. The reaction 2H2O → 2H2 + O2 is an example of:
(a) Combination reaction
(b) Decomposition reaction
(c) Displacement reaction
(d) Neutralization reaction
Correct answer - (b) Decomposition reaction
Q7. The reaction Fe + CuSO4 →FeSO4 + Cu is:
(a) Displacement reaction
(b) Double displacement reaction
(c) Combination reaction
(d) Decomposition reaction
Correct answer - (a) Displacement reaction
Q8. The reaction Na2SO4 + BaCl2 →BaSO4 + 2NaCl
(a) Combination reaction
(b) Displacement reaction
(c) Double displacement reaction
(d) Redox reaction
Correct answer - (c) Double displacement reaction
Q9. Na2SO4 + BaCl2 →BaSO4 + 2NaCl , which substance is the white precipitate formed in the reaction.
(a) 2NaCl
(b) BaSO4
(c) BaCl2
(d) Na2SO4
Correct answer - (b) BaSO4
Q10. A reaction in which heat is released is called:
(a) Endothermic reaction
(b) Reversible reaction
(c) Exothermic reaction
(d) Slow reaction
Correct answer - (c) Exothermic reaction
Q11. The reaction in which oxygen is gained is called:
(a) Reduction
(b) Oxidation
(c) Neutralization
(d) Redox
Correct answer - (b) Oxidation
Q12. Rancidity in food is caused dur to:
(a) Oxidation of oils and fats
(b) Evaporation of water
(c) Cooling of food
(d) Fermentation
Correct answer - (a) Oxidation of oils and fats
Q13. When magnesium ribbon burns in air, which solid substance is formed?
(a) Magnesium sulphate
(b) Magnesium oxide
(c) Magnesium carbonate
(d) Magnesium chloride
Correct answer - (b) Magnesium oxide
Q 14. The blue colour of copper sulphate solution turns green because of:
(a) Formation of copper oxide
(b) Formation of iron sulphate
(c) Formation of copper carbonate
(d) Formation of iron oxide
Correct answer - (b) Formation of iron sulphate
Q15. Which kind of energy is required in electrolysis of water?
(a) Light energy
(b) Heat energy
(c) Electrical energy
(d) Sound energy
Correct answer - (c) Electrical energy
Q16. In which reaction heat is absorbed?
(a) Exothermic reaction
(b) Neutralization
(c) Fast reaction
(d) Endothermic reaction
Correct answer - (d) Endothermic reaction
Q17. Rusting of iron occurs in the presence of :
(a) Air only
(b) Water only
(c) Air and moisture
(d) Sunlight and air
Correct answer - (c) Air and moisture
Q18. Which of the following is a balanced chemical equation?
(a) H2 + O2 →H2O
(b) 2H2 + O2 → 2H2O
(c) H2 + O2 →H2O2
(d) 2H2 + O2 →2H2O
Correct answer -(b) 2H2 + O2 → 2H2O
Q19. Which of the following is an example of a decomposition reaction caused by electricity?
(a) Decomposition of limestone
(b) Decomposition of water
(c) Decomposition of silver chloride
(d) All the above
Correct answer - (b) Decomposition of water
Q20. What is the colour of copper deposited on an iron nail copper sulphate solution?
(a) Green
(b) Brown
(c) Red
(d) Black
Correct answer - (b) Brown
Very Short
Answer Type Questions
Q1. What is a skeletal equation?
Answer
An
unbalanced chemical equation with unequal atoms on both sides.
Q2. Name the substance formed during burning of magnesium
ribbon.
Answer
Magnesium
oxide
Q3. Define combination reaction?
Answer
Two
substances combine to form one product.
Q4. What is corrosion?
Answer
Slow
damage of metals by air and moisture.
Q5. What is redox reaction?
Answer
Oxidation
and reduction occur together.
Q6. Which method is used to balance a chemical equation?
Answer
Hit and
trail
Q7. What is the chemical formula of slaked lime?
Answer – Ca(OH)2
Q8. What is precipitate?
Answer – An
insoluble solid substance
Short Answer
Types Questions
Q1. Differentiate between displacement and double
displacement reactions.
Answer -
|
Displacement reaction |
Double displacement reaction |
|
More reactive element replaces a less reactive
element from its compound |
Exchange of ions between two compounds. |
Q2. What are the necessary conditions for rusting of iron?
Answer
Rusting of iron occurs when both moisture and
oxygen present. When iron is exposed to air and water, it forms hydrated iron
oxide.
Q3. Explain exothermic and endothermic reactions.
Answer
|
Exothermic reaction |
Endothermic reaction |
|
Heat is released during the chemical reaction. |
Heat is absorbed during the chemical reaction. |
Q4. Give two examples from everyday life situation where
redox reaction takes place.
Answer
Corrosion
and rancidity are the examples of redox reaction in everyday life situation.
Q5. What happens when magnesium ribbon is burnt?
Answer
When a
magnesium ribbon is burnt, it burns with white dazzling flame and forms white
powder of magnesium oxide.
Q6. What is precipitation reaction?
Answer
A
chemical reaction in which an insoluble solid substance is formed, which is
called precipitate and the reaction is called precipitation reaction.
Long Answer
Type Questions
Q1. Explain types of following chemical reactions with
examples – (i) Combination reaction (ii) Decomposition reaction (iii)
Displacement reaction (iv) Double displacement reaction (v) Redox reaction
Answer
(i) Combination reaction: - The reaction in which two or more substances combine to form a single product is called combination reaction.
CaO + H2O →Ca(OH)2
(ii) Decomposition reaction :- The reaction in which a compound breaks into two or more simpler substances is called decomposition reaction. It requires energy in the form of heat, light or electricity.
2H2O →2H2 + O2
(iii) Displacement reaction: - The reaction in a more reactive element displaces a less reactive element from its compound.
Fe + CuSO4 →FeSO4 + Cu
(iv) Double displacement reaction:- The reaction in which two compounds exchange ions and form new compounds, is called double displacement reaction.
Na2SO4 + BaCl2 →BaSO4 + 2NaCl
(v) Redox reaction: - Oxidation and reduction occur simultaneously. This called redox reaction. One substance is oxidized and another is reduced.
CuO + H2 →H2O + Cu
Q2. What is
corrosion? Explain the methods used to prevent it.
Answer
Corrosion is the
gradual destruction of metal due to reaction with air and moisture. Rusting of
iron is a common example of corrosion.
When iron reacts
with oxygen and moisture, it forms hydrated iron oxide(rust)
4Fe + 3O2 +x H2O → 2Fe2O3.xH2O
Prevention Methods of Corrosion
1. Painting:
prevents contact with air and moisture
2. Oiling
and greasing: forms a protective layer
3. Galvanisation:
Coating iron with zinc
4. Alloying:
Mixing iron with other metals to make it corrosion resistant.
Q3. Explain redox reaction
with an example.
Answer
A redox reaction is a chemical reaction in which
oxidation and reduction occur at the same time. Oxidation means gain of oxygen or
loss of hydrogen , while reduction means loss of oxygen or gain of hydrogen.
One substance gets oxidised and another gets reduced
in a chemical reaction.
Example
CuO + H2 →Cu + H2O
Copper oxide reduced to copper after losing oxygen and
hydrogen is oxidised to water after gaining oxygen. So, this is a redox
reaction.
Q4. Explain the process of
electrolysis of water with chemical equation.
Answer
Electrolysis of water is a decomposition reaction on
passing electricity through water mixed with a few drops of acid.
Two electrodes are placed in the solution and
connected to a battery. When electricity is passed through the solution. Water decomposes
into hydrogen and oxygen. Hydrogen gas is collected at the cathode and oxygen
gas at the anode.
Chemical equation of Electrolysis of water
2H2O
→2H2
+ O2
By the4 electrolysis of water , hydrogen and oxygen
gases are formed in the ratio 2:1 by volume.
Diagram Based Questions
Q1. Draw a labelled diagram of electrolysis of water experiment.
Q2. Draw three test tube
experiment showing rusting of iron.
Q3. Draw a diagram of
experiment showing displacement reaction.
Q4. Draw a diagram of
burning of magnesium ribbon.
Case Study based Question
Read the passage and answer the questions
An iron nail is placed in copper sulphate solution. After some time, the blue colour fades and a brown layer appear on the nail.
i. Name the reaction occur.
Answer
Displacement reaction
ii. Write the balanced equation for the reaction.
Answer
Fe + CuSO4 →FeSO4 + Cu
iii. Which metal is more reactive?
Answer
Iron (Fe) is more reactive.
iv. Why does colour change?
Answer
Due to formation of Ferrous sulphate.
v. What is deposited on iron nail.
Answer
Copper metal
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