Bihar Board Class 10 Chemistry Notes 2025 | All Chapters, Formulas & MCQs

Chapter 1: Chemical Reactions and Equations

Key Topics

• Chemical Reaction

• Types of Reactions

• Balancing Equations

• Examples

Chemical Reaction

A process in which one or more substances (reactants) change to form new substances (products) with different properties.

General Form:
Reactants → Products

Example:
2H2+O2→2H2O2H2​+O2​→2H2​O

Types of Chemical Reactions

1. Combination Reaction – Two or more substances combine to form a single product.
   Example: CaO+H2O→Ca(OH)2CaO+H2​O→Ca(OH)2​

2. Decomposition Reaction – A single compound breaks into two or more substances.
   Example: 2KClO3→2KCl+3O22KClO3​→2KCl+3O2​

3. Displacement Reaction – A more reactive element displaces a less reactive one.
   Example: Zn+CuSO4→ZnSO4+CuZn+CuSO4​→ZnSO4​+Cu

4. Double Displacement Reaction – Exchange of ions between two compounds.
   Example: Na2SO4+BaCl2→BaSO4+2NaClNa2​SO4​+BaCl2​→BaSO4​+2NaCl

5. Oxidation and Reduction

   • Oxidation = Gain of Oxygen / Loss of Hydrogen

   • Reduction = Loss of Oxygen / Gain of Hydrogen

Chapter 2: Acids, Bases and Salts

Acids

• Sour in taste, turn blue litmus red.

• Produce H⁺ ions in solution.
  Example: HCl, H₂SO₄

Bases

• Bitter in taste, soapy to touch, turn red litmus blue.

• Produce OH⁻ ions in solution.
  Example: NaOH, KOH

Salts

• Formed by neutralization reaction between acid and base.
  Example: HCl + NaOH → NaCl + H₂O

Important Reactions

1. Reaction of Acids with Metals
   Zn+H2SO4→ZnSO4+H2Zn+H2​SO4​→ZnSO4​+H2​

2. Neutralization
   HCl+NaOH→NaCl+H2OHCl+NaOH→NaCl+H2​O

3. Reaction of Carbonates with Acids
   CaCO3+2HCl→CaCl2+CO2+H2OCaCO3​+2HCl→CaCl2​+CO2​+H2​O

pH Scale

• Measures acidity/basicity (0–14).

• pH < 7 → Acidic, pH = 7 → Neutral, pH > 7 → Basic.

Chapter 3: Metals and Non-Metals

Physical Properties of Metals

• Malleable, ductile, good conductors, lustrous.

Physical Properties of Non-Metals

• Brittle, poor conductors, non-lustrous.

Chemical Properties of Metals

1. Reaction with Oxygen
   4Na+O2→2Na2O4Na+O2​→2Na2​O

2. Reaction with Water
   2Na+2H2O→2NaOH+H22Na+2H2​O→2NaOH+H2​

3. Reaction with Acids
   Zn+2HCl→ZnCl2+H2Zn+2HCl→ZnCl2​+H2​

Reactivity Series

• Metals arranged in order of reactivity.

• Potassium, Sodium – highly reactive.

• Gold, Platinum – least reactive.

Extraction of Metals

• High reactivity: Electrolysis (Na, K).

• Medium reactivity: Roasting/Calcination (Zn, Fe).

• Low reactivity: Heat alone (Hg, Cu).

Chapter 4: Carbon and Its Compounds

Unique Properties of Carbon

• Catenation – Ability to form long chains.

• Tetravalency – 4 valence electrons.

Hydrocarbons

1. Alkanes (CₙH₂ₙ₊₂) – Single bonds (saturated). Example: CH₄

2. Alkenes (CₙH₂ₙ) – Double bond (unsaturated). Example: C₂H₄

3. Alkynes (CₙH₂ₙ₋₂) – Triple bond. Example: C₂H₂

Functional Groups

• Alcohol (-OH), Carboxylic Acid (-COOH), Aldehyde (-CHO), Ketone (-CO-).

Important Reactions

1. Combustion
   CH4+2O2→CO2+2H2O+HeatCH4​+2O2​→CO2​+2H2​O+Heat

2. Addition Reaction
   C2H4+H2→C2H6C2​H4​+H2​→C2​H6​

3. Substitution Reaction
   CH4+Cl2→CH3Cl+HClCH4​+Cl2​→CH3​Cl+HCl

Chapter 5: Periodic Classification of Elements

Mendeleev’s Periodic Table

• Arranged elements based on atomic mass.

Modern Periodic Table

• Arranged elements by atomic number.

Groups and Periods

• 18 Groups (vertical columns).

• 7 Periods (horizontal rows).

Periodic Trends

1. Atomic Size – Decreases across a period, increases down a group.

2. Electronegativity – Increases across a period, decreases down a group.

3. Metallic Character – Decreases across a period, increases down a group.

Chapter 6: Periodic Properties (Bihar Board Special Focus)

Some Bihar Board books also highlight:

• Valency variation.

• Importance of classification.

• Predicting properties using periodic table.

Important Formulas in Chemistry

1. Molecular Formula of Hydrocarbons

   • Alkane: CₙH₂ₙ₊₂

   • Alkene: CₙH₂ₙ

   • Alkyne: CₙH₂ₙ₋₂

2. pH Calculation
   pH=−log⁡[H+]pH=−log[H+]

3. Molar Mass = Atomic Mass × Number of Atoms

4. Faraday’s Law (Electrolysis)
   Mass deposited ∝ Charge passed.

Quick Revision Points

• Always balance equations.

• Remember reactivity series (K, Na, Ca, Mg, Al, Zn, Fe, Pb, H, Cu, Ag, Au).

• Acids release H⁺, Bases release OH⁻.

• Metals are reducing agents, Non-metals are oxidizing agents.

• Carbon compounds: Covalent bonds only.

• Modern Periodic Table: Based on atomic number, not mass.

Important Objective Questions – Bihar Board Class 10 Chemistry

Q1. Which gas is evolved when zinc reacts with dilute sulphuric acid?

A) Oxygen
B) Carbon dioxide
C) Hydrogen
D) Nitrogen
Answer: Hydrogen

Q2. The reaction between acid and base is called?

A) Combination reaction
B) Displacement reaction
C) Neutralization reaction
D) Oxidation reaction
Answer: Neutralization

Q3. What is the pH value of pure water at 25°C?

A) 5
B) 6
C) 7
D) 8
Answer: 7

Q4. Which acid is present in vinegar?

A) Hydrochloric acid
B) Sulphuric acid
C) Acetic acid
D) Nitric acid
Answer: Acetic acid

Q5. Name a metal that does not react with water.

A) Sodium
B) Calcium
C) Zinc
D) Gold
Answer: Gold

Q6. What is the general formula of alkanes?

A) CₙH₂ₙ₊₂
B) CₙH₂ₙ
C) CₙH₂ₙ₋₂
D) CH₃OH
Answer: CₙH₂ₙ₊₂

Q7. Which element is called the “basis of life”?

A) Oxygen
B) Hydrogen
C) Carbon
D) Nitrogen
Answer: Carbon

Q8. Who proposed the Modern Periodic Table?

A) Mendeleev
B) Newlands
C) Moseley
D) Dalton
Answer: Moseley

Q9. Which metal is stored in kerosene oil?

A) Aluminium
B) Sodium
C) Iron
D) Copper
Answer: Sodium

Q10. Which gas turns lime water milky?

A) Oxygen
B) Carbon dioxide
C) Hydrogen
D) Ammonia
Answer: Carbon dioxide

Q11. What is the chemical formula of washing soda?

A) NaCl
B) NaOH
C) Na₂CO₃·10H₂O
D) CaCO₃
Answer: Na₂CO₃·10H₂O

Q12. What is the chemical name of bleaching powder?

A) Calcium hydroxide
B) Calcium carbonate
C) Calcium oxychloride
D) Calcium chloride
Answer: Calcium oxychloride

Q13. Which acid is called the king of chemicals?

A) HNO₃
B) H₂SO₄
C) HCl
D) CH₃COOH
Answer: H₂SO₄

Q14. The atomic number of oxygen is?

A) 6
B) 7
C) 8
D) 9
Answer: 8

Q15. Which non-metal is a good conductor of electricity?

A) Sulphur
B) Graphite
C) Phosphorus
D) Oxygen
Answer: Graphite

Q16. Which property decreases across a period in the periodic table?

A) Metallic character
B) Atomic size
C) Electronegativity
D) Valency
Answer: Atomic size

Q17. Which property increases down a group in the periodic table?

A) Non-metallic character
B) Ionization energy
C) Metallic character
D) Electronegativity
Answer: Metallic character

Q18. Which metal is used in thermometers?

A) Copper
B) Aluminium
C) Mercury
D) Lead
Answer: Mercury

Q19. The reaction 2KClO₃ → 2KCl + 3O₂ is an example of?

A) Combination reaction
B) Double displacement reaction
C) Decomposition reaction
D) Displacement reaction
Answer: Decomposition

Q20. Which functional group is present in ethanol?

A) –COOH
B) –OH
C) –CHO
D) –CO–
Answer: –OH

Conclusion

This Bihar Board Class 10 Chemistry Notes is designed for fast revision before exams. It covers all chapters, formulas, reactions, and examples in a simplified manner. If you study these notes regularly, scoring 90+ in Chemistry will become easier.

Bihar Board Class 10 Chemistry