NDA (National Defence Academy) Exam General Science (GAT Paper II, Part B) Syllabus

What is electromagnetic induction, and who discovered it?

Electromagnetic induction is the production of an electromotive force (voltage) in a conductor when the magnetic flux through it changes; discovered by Michael Faraday. It is the basis of generators and transformers.

Distinguish between AC and DC current.

Direct current (DC) flows in one constant direction (e.g. batteries); alternating current (AC) periodically reverses direction (e.g. mains supply, 50 Hz in India). AC is easier to transmit over long distances using transformers.

List the seven SI base units and the quantities they measure.

Metre (length), kilogram (mass), second (time), ampere (electric current), kelvin (temperature), mole (amount of substance), and candela (luminous intensity).

Name the instruments used to measure (a) atmospheric pressure, (b) temperature, (c) electric current, (d) potential difference.

(a) Barometer, (b) thermometer, (c) ammeter (connected in series), (d) voltmeter (connected in parallel).

What does a galvanometer detect, and what is a fuse used for?

A galvanometer detects and measures small electric currents. A fuse is a safety device with a thin wire of low melting point that melts and breaks the circuit when current exceeds a safe limit, preventing damage/fire.

Distinguish a physical change from a chemical change with one example each.

A physical change alters form/state but no new substance forms and it is usually reversible (e.g. melting of ice). A chemical change forms a new substance and is usually irreversible (e.g. rusting of iron, burning of paper).

List the main types of chemical reactions.

Combination (synthesis), decomposition, displacement, double displacement, oxidation-reduction (redox), and neutralization (acid + base -> salt + water).

Define an exothermic and an endothermic reaction with an example.

Exothermic reactions release heat (e.g. combustion, respiration). Endothermic reactions absorb heat (e.g. photosynthesis, decomposition of calcium carbonate).

Name the three subatomic particles of an atom with their charge and location.

Proton (positive charge, in nucleus), neutron (no charge, in nucleus), and electron (negative charge, orbiting the nucleus in shells).

Define atomic number and mass number.

Atomic number (Z) = number of protons in the nucleus (defines the element). Mass number (A) = total number of protons and neutrons in the nucleus. Number of neutrons = A − Z.

What are isotopes? Give an example.

Isotopes are atoms of the same element with the same atomic number (protons) but different mass numbers (different numbers of neutrons), e.g. carbon-12, carbon-13 and carbon-14, or protium, deuterium and tritium of hydrogen.

Distinguish ionic and covalent bonding.

Ionic bonding forms by transfer of electrons between a metal and a non-metal, creating charged ions held by electrostatic attraction (e.g. NaCl). Covalent bonding forms by sharing electrons between non-metals (e.g. H2O, CO2).

Define pH and state the pH ranges for acids, bases and neutral substances.

pH measures the hydrogen-ion concentration (acidity/alkalinity) on a scale of 0–14. pH < 7 is acidic, pH = 7 is neutral (pure water), pH > 7 is basic/alkaline.

Give the chemical names and formulae of common lime, baking soda and washing soda.

Lime/quicklime is calcium oxide (CaO); baking soda is sodium bicarbonate (NaHCO3); washing soda is sodium carbonate decahydrate (Na2CO3·10H2O).

What gas is produced when a metal reacts with a dilute acid, and how is it tested?

Hydrogen gas is produced. It is tested by bringing a burning splint near it, which extinguishes with a characteristic 'pop' sound.

State the composition of air by approximate percentage of major gases.

Nitrogen about 78%, oxygen about 21%, argon about 0.9%, carbon dioxide about 0.04%, plus traces of other gases and water vapour.

Name an alloy of (a) brass, (b) bronze, (c) stainless steel and their main constituents.

(a) Brass = copper + zinc; (b) bronze = copper + tin; (c) stainless steel = iron + chromium + nickel (with carbon).

What is the chemical name of common salt, chalk/marble, and the main constituent of glass?

Common salt is sodium chloride (NaCl); chalk and marble are calcium carbonate (CaCO3); glass is mainly silica/silicon dioxide (SiO2) with soda and lime.

Distinguish hard water from soft water and name a cause of hardness.

Hard water does not lather easily with soap; soft water lathers readily. Hardness is caused by dissolved calcium and magnesium salts (bicarbonates, chlorides, sulphates).

What is the difference between soaps and detergents?

Soaps are sodium/potassium salts of long-chain fatty acids and do not work well in hard water (form scum). Detergents are synthetic cleansing agents that work in both hard and soft water.

Name the four major biomolecules essential to life and their building blocks.

Carbohydrates (from sugars/monosaccharides), proteins (from amino acids), lipids/fats (from fatty acids and glycerol), and nucleic acids DNA/RNA (from nucleotides).

Differentiate prokaryotic and eukaryotic cells.

Prokaryotic cells (bacteria) lack a true membrane-bound nucleus and membrane-bound organelles. Eukaryotic cells (plants, animals, fungi, protists) have a true nucleus and membrane-bound organelles.

Name the cell organelle called the 'powerhouse of the cell' and the one that performs photosynthesis.

The mitochondrion is the powerhouse (produces ATP energy through respiration). The chloroplast (containing chlorophyll) performs photosynthesis in plant cells.

Write the overall word equation for photosynthesis.

Carbon dioxide + water --(sunlight, chlorophyll)--> glucose + oxygen. (6CO2 + 6H2O -> C6H12O6 + 6O2).

Name the main human blood groups and state which is the universal donor and universal recipient.

Blood groups are A, B, AB and O (with Rh + or −). O-negative is the universal donor; AB-positive is the universal recipient.

List the major systems of the human body and name the organ that pumps blood.

Digestive, respiratory, circulatory, nervous, excretory, skeletal, muscular, endocrine, and reproductive systems. The heart pumps blood through the circulatory system.

Name the deficiency diseases caused by lack of vitamin C, vitamin D, and iron.

Lack of vitamin C causes scurvy; lack of vitamin D causes rickets (in children); lack of iron causes anaemia.

Differentiate communicable and non-communicable diseases with an example each.

Communicable (infectious) diseases spread from person to person via pathogens (e.g. tuberculosis, malaria, COVID-19). Non-communicable diseases do not spread (e.g. diabetes, hypertension, cancer).

List the five kingdoms of biological classification (Whittaker's system).

Monera (bacteria), Protista (single-celled eukaryotes), Fungi, Plantae (plants), and Animalia (animals).

Define food chain and ecosystem, and name the producers in most food chains.

A food chain is the sequence of who eats whom, showing energy flow (producer -> consumer -> decomposer). An ecosystem is a community of living organisms interacting with their non-living environment. Green plants (autotrophs) are the producers.