Last-Minute Science Formulas & Chemical Reactions Revision for CBSE Class 10 Board Exam

The CBSE Class 10 Science Board Exam 2026, scheduled on 25 February 2026, is a crucial milestone for students across India. In the final days before the exam, smart revision is more effective than starting new topics. A focused review of important Science formulas, chemical reactions, definitions, and diagrams can significantly improve your score.

This last-minute revision covers the most important CBSE Class 10 Science formulas and chemical reactions from Physics, Chemistry, and Biology to help you revise quickly and confidently before the board exam.

Important Chemical Reactions for CBSE Class 10 Science Exam 2026

Chemical reactions are extremely important for scoring high marks in the board exam. Students should revise balanced equations and understand the type of reaction.

Types of Chemical Reactions

1. Combination Reaction

Two or more substances combine to form a single product.
Example:
CaO + H₂O → Ca(OH)₂

2. Decomposition Reaction

A compound breaks into simpler substances by heat, light, or electricity.
Example:
CaCO₃ (heat) → CaO + CO₂

3. Displacement Reaction

A more reactive element replaces a less reactive element from its compound.
Example:
Zn + CuSO₄ → ZnSO₄ + Cu

4. Double Displacement Reaction

Exchange of ions between two compounds.
Example:
Na₂SO₄ + BaCl₂ → BaSO₄ + 2NaCl

5. Redox Reaction

Oxidation and reduction occur together.
Example:
CuO + H₂ → Cu + H₂O

Remember:
Oxidation = Gain of oxygen or loss of hydrogen
Reduction = Loss of oxygen or gain of hydrogen

Balanced chemical equations are frequently asked in the CBSE Class 10 Science Board Exam 2026, so practice writing them clearly.

Important Reactions from Metals and Non-Metals

The important reactions from Metals and Non-Metals are frequently asked in the CBSE Class 10 Science Board Exam. Students must clearly understand reactions with oxygen, water, and acids, along with corrosion. Revise the key balanced chemical equations carefully — check below for examples.

Reaction of metals with oxygen:
2Mg + O₂ → 2MgO

Reaction of sodium with water:
2Na + 2H₂O → 2NaOH + H₂

Reaction of zinc with acid:
Zn + 2HCl → ZnCl₂ + H₂

Corrosion (Rusting of Iron):
4Fe + 3O₂ + xH₂O → 2Fe₂O₃·xH₂O

These reactions are commonly asked as short-answer or long-answer questions.

Acids, Bases and Salts: Quick Revision for Boards

Acids, Bases and Salts is a high-weightage chapter in the CBSE Class 10 Science Board Exam. Students should revise properties of acids and bases, the pH scale, common reactions, and important compounds like baking soda and washing soda. Focus on key equations and concepts — check below for quick revision points.

Acids release H⁺ ions in aqueous solution.
Bases release OH⁻ ions.

The pH scale ranges from 0 to 14:
pH < 7 → Acidic
pH = 7 → Neutral
pH > 7 → Basic

Important reactions:

Acid + Metal → Salt + Hydrogen
Zn + 2HCl → ZnCl₂ + H₂

Acid + Carbonate → Salt + Water + CO₂
Na₂CO₃ + 2HCl → 2NaCl + H₂O + CO₂

Formation of Plaster of Paris:
CaSO₄·2H₂O (heat) → CaSO₄·½H₂O + 1½H₂O

Important compounds to revise:
• Baking Soda – NaHCO₃
• Washing Soda – Na₂CO₃·10H₂O
• Bleaching Powder – CaOCl₂

These topics carry consistent weightage in CBSE Class 10 Science exams.

Carbon and Its Compounds: Important Concepts

Carbon forms covalent bonds by sharing electrons.

Important compounds:
Methane – CH₄
Ethanol – C₂H₅OH
Ethanoic Acid – CH₃COOH

Functional groups:
–OH → Alcohol
–COOH → Carboxylic acid

Properties of ethanol:
• Colourless liquid
• Soluble in water
• Used as solvent and fuel

Chemical properties and reactions of ethanol and ethanoic acid are important for board exams.

Important Physics Formulas for CBSE Class 10 Board Exam 2026

Physics formulas are scoring if written with correct units and steps.

1. Electricity Formulas

Ohm’s Law:
V = IR

Resistance:
R = V/I

Electric Power:
P = VI
P = I²R
P = V²/R

Electrical Energy:
E = P × t

Unit of Power = Watt
Unit of Energy = Joule
Commercial Unit of Energy = kWh

Electricity numericals are highly important in the CBSE Class 10 Science Board Exam.

2. Light – Reflection and Refraction

Mirror Formula:
1/f = 1/v + 1/u

Magnification (Mirror):
m = –v/u

Lens Formula:
1/f = 1/v – 1/u

Magnification (Lens):
m = v/u

Power of Lens:
P = 1/f (f in meters)

Students must remember the sign convention carefully.

3. Human Eye and Defects

Myopia → Corrected by concave lens
Hypermetropia → Corrected by convex lens
Presbyopia → Age-related defect

Ray diagrams are frequently asked in exams.

4. Magnetic Effects of Electric Current

Force on a conductor:
F = BIL

Right-Hand Thumb Rule
Fleming’s Left-Hand Rule
Fleming’s Right-Hand Rule

5. Work, Power and Energy

Work Done:
W = F × s

Kinetic Energy:
KE = ½mv²

Potential Energy:
PE = mgh

Power:
P = W/t

Unit of Work and Energy = Joule

Important Biology Topics for Quick Revision

Important Biology topics for quick revision in the CBSE Class 10 Science Board Exam include Life Processes, Control and Coordination, Reproduction, Heredity, and Environment-related chapters. Focus on definitions, diagrams, and key processes like photosynthesis and respiration. Revise important points carefully. check below for details.

Life Processes include:
Nutrition, Respiration, Transportation, Excretion

Photosynthesis Equation:
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

Human heart has four chambers.
Nephron is the functional unit of kidney.
Brain is divided into forebrain, midbrain, and hindbrain.

Biology questions are often direct from NCERT, so revise definitions carefully.

Last-Minute Preparation Tips for CBSE Class 10 Science Board Exam 2026

Last-Minute Preparation Tips for CBSE Class 10 Science Board Exam 2026 are essential to boost confidence and accuracy before the exam. Focus on revising formulas, balanced chemical reactions, key diagrams, and important definitions. Practice a few numericals and avoid new topics. Check below for detailed tips.

• Revise formulas at least twice before 25 February 2026.
• Practice writing balanced chemical equations clearly.
• Solve 4–5 numericals from Electricity and Light chapters.
• Revise important diagrams such as human eye, heart, electric circuit, and ray diagrams.
• Write answers neatly with proper units and steps.
• Avoid studying new topics at the last moment.