The NDA (National Defence Academy) & CDS (Combined Defence Services) Exams are conducted by UPSC to recruit candidates for the Indian Armed Forces. The written exam tests core subjects including Mathematics, English, General Knowledge, and General Science (Physics, Chemistry & Biology). In Chemistry, questions are mainly conceptual, basic, and application-based, often asked in MCQ format. Understanding fundamental principles is essential for scoring well in the General Knowledge section.
1. Acids, Bases and Salts – Overview
Introduction
Acids, bases, and salts are fundamental chemical substances that play key roles in daily life and industrial processes. NDA/CDS exams frequently test their properties, examples, reactions, and applications.
Subtopics
Definition and Characteristics
Properties of acids (taste, pH, reactions)
Properties of bases (feel, reaction with indicators)
Salts as neutralization products
Types of Acids and Bases
Strong vs weak acids
Strong vs weak bases
Mineral acids vs organic acids
pH Scale
Meaning of pH
Acidic, basic, and neutral solutions
Importance of pH in daily life
Indicators
Litmus, phenolphthalein, methyl orange
Natural indicators
Neutralization Reactions
Acid + Base → Salt + Water
Applications (antacids, agriculture, industry)
Common Salts and Their Uses
Sodium chloride, baking soda, washing soda, plaster of Paris
Chemical formulas and uses
Conclusion
Understanding acids, bases, and salts helps decode many real-life reactions and is a high-yield topic for NDA/CDS exams. Mastery of their properties and examples ensures strong command over basic chemistry.
2. Elements, Compounds and Mixtures – Overview
Introduction
Matter exists in various forms, and its classification into elements, compounds, and mixtures forms the foundation of chemistry. NDA/CDS MCQs often test definitions, differences, and examples.
Subtopics
Elements
Definition and characteristics
Metals, non-metals, metalloids
Common examples and uses
Compounds
Chemical bonding and fixed composition
Examples: water, carbon dioxide, sodium chloride
Difference between compounds and mixtures
Mixtures
Homogeneous vs heterogeneous mixtures
Examples: air, salt solution, sand & iron fillings
Methods of Separation of Mixtures
Filtration
Evaporation
Distillation
Sublimation
Chromatography
Chemical & Physical Changes
Identifying features
Real-world examples
Conclusion
A clear understanding of elements, compounds, and mixtures helps build a strong conceptual foundation in chemistry. These basics are repeatedly tested in NDA/CDS and form the base for further chemical study.
SME(General Science), SSBCrackExams, GATE Qualified, M.Sc.(Biochemistry) from Allahabad University, B.Sc. from Ewing Christian College(Prayagraj).Knows English & Hindi.
