Part 3: Important Questions, Answers and Revision Notes
VERY SHORT ANSWER QUESTIONS
Q1. What is a chemical reaction?
A chemical reaction is a process in which one or more substances react to form new substances with different properties.
Q2. Name the substances which take part in a chemical reaction.
The substances which take part in a chemical reaction are called reactants.
Q3. What are products?
The new substances formed after a chemical reaction are called products.
Q4. What is a chemical equation?
A chemical equation is the representation of a chemical reaction using symbols and formulas.
Q5. What is oxidation?
Oxidation is a chemical reaction in which a substance gains oxygen or loses hydrogen.
Q6. What is reduction?
Reduction is a chemical reaction in which a substance loses oxygen or gains hydrogen.
SHORT ANSWER QUESTIONS
Q1. What is a balanced chemical equation?
A balanced chemical equation is one in which the number of atoms of each element is equal on both sides of the equation.
Q2. Why should a chemical equation be balanced?
A chemical equation should be balanced to satisfy the law of conservation of mass.
Q3. What is corrosion?
Corrosion is the slow eating away of metals by the action of air, moisture or chemicals.
Example: Rusting of iron.
Q4. What is rancidity?
Rancidity is the process in which fats and oils get oxidised and spoil the food.
LONG ANSWER QUESTIONS
Q1. Explain oxidation and reduction with an example.
Oxidation and reduction always occur together in a chemical reaction.
Example:
CuO + H₂ → Cu + H₂O
Oxidation:
Hydrogen gains oxygen to form water, so hydrogen is oxidised.
Reduction:
Copper oxide loses oxygen to form copper, so copper oxide is reduced.
Such reactions are called redox reactions.
Q2. Explain the effects of oxidation in daily life.
The effects of oxidation in daily life are:
- Corrosion:
Metals like iron react with air and moisture and get damaged. This process is called corrosion. - Rancidity:
Food items containing oil and fat get oxidised and spoil. This process is called rancidity.
IMPORTANT KEYWORDS (REVISION)
- Chemical Reaction
- Reactants
- Products
- Chemical Equation
- Balanced Equation
- Oxidation
- Reduction
- Corrosion
- Rancidity
- Redox Reaction
COMPLETED