The NDA CDS 1 2026 Examination is a national-level defence entrance test conducted by the UPSC for recruitment into the Indian Army, Navy, and Air Force. Chemistry forms an important part of the General Science section, where questions are mainly concept-based, objective, and application-oriented.
In this class, we will revise key concepts from Atomic Structure and Industrial Chemistry (Cement and Paints) that frequently appear in MCQs.

Topic 1: Atomic Structure

Subtopics

1.1 Early Theories of Atom

• Dalton’s atomic theory
• Thomson’s Plum Pudding Model
• Rutherford’s Nuclear Model
• Bohr’s Atomic Model

1.2 Fundamental Particles

• Electron – charge, mass, discovery (J.J. Thomson)
• Proton – discovery (Goldstein)
• Neutron – discovery (Chadwick)

1.3 Atomic Number, Mass Number, Isotopes

• Definitions and examples
• Applications of isotopes (medicine, industry)

1.4 Electronic Configuration

• Aufbau principle
• Hund’s rule
• Pauli’s exclusion principle
• Writing configurations for first 20 elements

1.5 Quantum Numbers (Basics for MCQs)

• Principal, azimuthal, magnetic, spin
• Shapes of s, p, d orbitals

1.6 Bohr’s Model and Limitations

• Energy levels
• Line spectra of hydrogen

Topic 2: Preparation & Properties of Cement and Paints

Subtopics

2.1 Cement

Preparation / Manufacturing

• Raw materials: limestone, clay
• Steps:
  • Crushing and grinding
  • Heating in rotary kiln (clinker formation)
  • Grinding with gypsum

Properties

• Setting and hardening
• Composition of Portland cement (C₂S, C₃S, C₃A)
• Uses in construction

2.2 Types of Cement (Basics for MCQs)

• Ordinary Portland Cement (OPC)
• White cement
• Quick-setting cement
• Blast furnace slag cement

2.3 Paints

Composition of Paints

• Pigment
• Binder (vehicle)
• Solvent
• Additives

Types of Paints

• Enamel paints
• Emulsion paints
• Distemper
• Oil paints

Properties and Uses

• Protection from corrosion
• Aesthetic appearance
• Coating on metal, wood, walls

Drying and Setting of Paints

• Oxidation, polymerization, evaporation of solvent

Conclusion

In the NDA CDS 1 2026 exam, Chemistry MCQs evaluate your understanding of basic principles rather than numerical problem-solving. Concepts from Atomic Structure and Industrial Chemistry (including cement and paints) are frequently asked due to their practical relevance.
A strong grasp of definitions, properties, and processes will help you score efficiently and boost your overall General Science performance.