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| General Science: Important Facts and MCQs for SSC, UPSC |
Last Updated: 07 October 2026, 01:25 PM IST | Reviewed by Vijay Sah
General Science is an important part of the General Awareness section in SSC, Railway, Banking, Defence and other competitive examinations. Questions are commonly asked from Physics, Chemistry, Biology, Environment and everyday science. Most questions test basic concepts, scientific facts, units, human body systems, diseases, chemical reactions, energy, light, sound and common applications of science.
This General Science GK guide brings together important concepts that students should revise before competitive exams. The focus is on facts that are frequently useful in objective-type questions rather than advanced scientific theory.
Key Points at a Glance: Physics covers motion, force, work, energy, electricity, light and sound. Chemistry focuses on matter, elements, compounds, acids, bases and chemical reactions. Biology covers cells, human body systems, nutrition, diseases and genetics. Environment and space science add another important group of exam questions.
Quick Links
Quick Facts
| Point | Fact |
|---|---|
| SI Unit of Force | Newton (N) |
| SI Unit of Work | Joule (J) |
| SI Unit of Power | Watt (W) |
| SI Unit of Electric Current | Ampere (A) |
| SI Unit of Temperature | Kelvin (K) |
| Basic Unit of Life | Cell |
| Largest Human Organ | Skin |
| Red Pigment in Blood | Haemoglobin |
| Photosynthesis | Plants use light energy to make food from carbon dioxide and water |
| pH of Neutral Solution | 7 at 25°C |
| Planet Nearest to the Sun | Mercury |
| Largest Planet | Jupiter |
Physics: Important Concepts
Motion and Speed
Motion describes a change in the position of an object with time. Speed tells how fast an object covers distance, while velocity includes both speed and direction. The SI unit of speed is metre per second (m/s).
Background: Motion is a basic concept used to understand vehicles, falling objects, planetary movement and many mechanical systems.
Exam use: Competitive exams often ask the difference between speed and velocity or the formula for average speed.
Exam Point: Speed = Distance ÷ Time.
Force and Newton's Laws
Force is a push or pull that can change the motion, direction or shape of an object. The SI unit of force is the newton. Newton's laws of motion explain the relationship between force, mass and acceleration.
Quick context: The second law is commonly expressed as F = ma, where F is force, m is mass and a is acceleration.
Exam use: Questions may ask which law explains inertia, action-reaction or the relation between force and acceleration.
Exam Point: Newton's first law is associated with inertia.
Work, Energy and Power
Work is done when a force causes displacement in the direction of the force. Energy is the capacity to do work, while power describes the rate at which work is done. Their SI units are joule for work and energy and watt for power.
Why it matters: These concepts appear in questions involving machines, electricity, mechanical motion and energy conversion.
Exam use: Remember that power is measured in watt and one watt equals one joule per second.
Exam Point: Power = Work ÷ Time.
Heat and Temperature
Heat is energy transferred because of a temperature difference, while temperature indicates the degree of hotness or coldness of a body. Heat can be transferred by conduction, convection and radiation.
Common mistake: Heat and temperature are not the same physical quantity. A large object and a small object can have the same temperature but different amounts of thermal energy.
Exam use: Questions frequently connect conduction with solids, convection with fluids and radiation with heat transfer through electromagnetic waves.
Exam Point: Radiation does not require a material medium.
Light
Light is electromagnetic radiation that can travel through a vacuum. Reflection is the bouncing back of light from a surface, while refraction is the change in direction of light when it passes from one medium to another.
Quick context: Mirrors mainly demonstrate reflection, while lenses use refraction to form images.
Exam use: Students should remember the basic differences between concave and convex mirrors and between convex and concave lenses.
Exam Point: A convex lens is thicker at the centre than at the edges.
Sound
Sound is produced by vibrations and requires a material medium for propagation. It cannot travel through a vacuum. Frequency determines the pitch of a sound, while amplitude is related to its loudness.
Background: Sound waves are mechanical waves because they require a medium such as air, water or a solid.
Exam use: Questions commonly ask about frequency, pitch, loudness, echo and the speed of sound.
Exam Point: Higher frequency means higher pitch.
Electricity
Electric current is the flow of electric charge. Its SI unit is ampere. Voltage is measured in volts, resistance in ohms and electrical power in watts.
Quick context: Ohm's law states that, under suitable constant physical conditions, current through a conductor is proportional to the potential difference across it. It is commonly written as V = IR.
Exam use: Questions often test units, circuit components, Ohm's law and the difference between conductors and insulators.
Exam Point: Resistance is measured in ohms (Ω).
Chemistry: Important Concepts
Matter and Its States
Matter is anything that has mass and occupies space. The common states of matter are solid, liquid and gas. In a solid, particles are relatively closely arranged; in liquids they can move past one another, while gases have much greater freedom of movement.
Background: Changes of state include melting, freezing, evaporation, condensation and sublimation.
Exam use: Objective questions often ask which change involves solid directly changing into gas or gas changing into liquid.
Exam Point: Solid directly changing into gas is called sublimation.
Elements, Compounds and Mixtures
An element contains one type of atom, while a compound contains elements chemically combined in a fixed proportion. A mixture contains substances physically combined and its components can generally be separated by physical methods.
Common mistake: A compound is not the same as a mixture. The properties of a compound can differ greatly from those of its constituent elements.
Exam use: Questions may ask whether air, water, oxygen or brass is an element, compound or mixture.
Exam Point: Air is a mixture of gases.
Atoms and Molecules
An atom is the basic unit of an element that retains its chemical identity. A molecule consists of two or more atoms chemically bonded together. Atoms contain subatomic particles such as protons, neutrons and electrons.
Quick context: Protons carry positive charge, electrons carry negative charge and neutrons have no electric charge.
Exam use: Basic questions may ask the charge or location of subatomic particles.
Exam Point: The nucleus contains protons and neutrons.
Acids, Bases and Salts
Acids and bases have different chemical properties. Acids generally produce hydrogen ions in aqueous solution, while bases produce hydroxide ions in many common aqueous systems. A salt can be formed through reactions such as neutralisation between an acid and a base.
Background: The pH scale is commonly used to describe how acidic or basic an aqueous solution is. A pH of 7 is neutral at 25°C.
Exam use: Questions often involve common substances such as hydrochloric acid, sodium hydroxide, baking soda and common salt.
Exam Point: A solution with pH below 7 is acidic at 25°C.
Metals and Non-Metals
Metals generally show properties such as good electrical and thermal conductivity, malleability and ductility. Non-metals generally show different physical and chemical properties, although there are exceptions.
Quick context: Metals can form alloys by combining with other elements. Brass, for example, is an alloy mainly of copper and zinc.
Exam use: Competitive exams frequently ask about conductivity, corrosion, alloys and common uses of metals.
Exam Point: Stainless steel is an alloy, not a pure element.
Chemical Reactions
A chemical reaction produces one or more new substances. Common types include combination, decomposition, displacement, double displacement and oxidation-reduction reactions.
Why it matters: Everyday processes such as rusting, combustion, digestion and photosynthesis involve chemical changes.
Exam use: Students should be able to distinguish physical changes from chemical changes and identify basic reaction types.
Exam Point: Rusting of iron is a chemical change.
Biology: Important Concepts
Cell: Basic Unit of Life
The cell is the basic structural and functional unit of life. Cells may be broadly classified as prokaryotic or eukaryotic. Plant and animal cells share many structures but also have important differences.
Quick context: The nucleus contains genetic material in eukaryotic cells. Plant cells have structures such as a cell wall and chloroplasts that are not present in typical animal cells.
Exam use: Questions commonly ask about mitochondria, ribosomes, chloroplasts, nucleus and cell membrane.
Exam Point: Mitochondria are major sites of aerobic cellular respiration and ATP production.
Human Digestive System
The digestive system breaks food into simpler substances that can be absorbed and used by the body. The major organs include the mouth, oesophagus, stomach, small intestine and large intestine, along with associated organs such as the liver and pancreas.
Background: Most nutrient absorption takes place in the small intestine.
Exam use: Competitive exams often ask about digestive enzymes, bile, absorption and the functions of different organs.
Exam Point: Bile is produced by the liver and stored in the gallbladder.
Respiratory System
The respiratory system brings oxygen into the body and removes carbon dioxide. In humans, gas exchange takes place mainly in the alveoli of the lungs.
Quick context: Oxygen is used in cellular respiration to help release energy from nutrients, while carbon dioxide is produced as a waste product of aerobic respiration.
Exam use: Questions commonly focus on lungs, alveoli, breathing and exchange of gases.
Exam Point: Alveoli provide a large surface area for gas exchange.
Blood and Circulation
Blood transports oxygen, nutrients, hormones and waste materials. It contains plasma, red blood cells, white blood cells and platelets. The human heart pumps blood through the circulatory system.
Why it matters: Red blood cells contain haemoglobin, which helps transport oxygen. White blood cells are involved in immune defence, while platelets help in blood clotting.
Exam use: Questions may ask about blood components, heart chambers, arteries, veins and circulation.
Exam Point: Haemoglobin gives red blood cells their characteristic colour and helps carry oxygen.
Photosynthesis
Photosynthesis is the process by which green plants use light energy to make organic food from carbon dioxide and water, with oxygen released as a by-product under typical oxygenic photosynthesis.
Background: Chlorophyll absorbs light energy needed for photosynthesis.
Exam use: Questions commonly ask about the raw materials, role of sunlight, chlorophyll and gases involved in the process.
Exam Point: Carbon dioxide and water are the main raw materials for photosynthesis.
Vitamins and Deficiency Diseases
Vitamins are organic compounds required in small amounts for normal body functions. Different vitamins perform different roles, and their deficiencies can cause characteristic health problems.
Quick context: Vitamin A deficiency can cause night blindness, vitamin C deficiency can cause scurvy, and vitamin D deficiency can lead to rickets in children.
Exam use: Vitamin-deficiency pairs are common in General Science objective questions.
Exam Point: Vitamin C deficiency is associated with scurvy.
Immunity and Vaccines
The immune system protects the body against harmful pathogens. Vaccines train the immune system to recognise specific disease-related antigens and develop an immune response, helping the body respond more effectively to later exposure.
Quick context: Depending on the vaccine, the immune-stimulating component may involve an antigen or genetic instructions for producing an antigen.
Exam use: Questions can ask about antibodies, antigens, immunity and the purpose of vaccination.
Exam Point: Vaccination works by preparing the immune system to respond to a specific disease-causing agent.
Genetics and Heredity
Genetics is the study of heredity and variation. Genes are units of heredity carried on chromosomes and are made of DNA sequences that provide information used by cells.
Background: Gregor Mendel's experiments with pea plants helped establish basic principles of heredity.
Exam use: Questions often involve genes, chromosomes, DNA, dominant and recessive traits and Mendel.
Exam Point: DNA is the principal hereditary material in humans.
Environment and Space Science
Food Chain and Ecosystem
An ecosystem includes living organisms and their physical surroundings interacting with one another. A food chain represents the transfer of energy and nutrients from one organism to another through feeding relationships.
Quick context: Producers such as green plants form the base of many food chains, followed by consumers and decomposers.
Exam use: Questions commonly ask about producers, consumers, decomposers, food chains and food webs.
Exam Point: Green plants are primary producers in most terrestrial ecosystems.
Pollution
Pollution occurs when harmful substances or forms of energy enter the environment and cause undesirable changes. Major types include air, water, soil and noise pollution.
Why it matters: Pollutants can affect human health, ecosystems, water quality and climate-related processes.
Exam use: Questions may ask about major pollutants, sources of pollution, acid rain, smog and greenhouse gases.
Exam Point: Sulfur dioxide and nitrogen oxides are important contributors to acid deposition.
Renewable and Non-Renewable Energy
Renewable energy sources are naturally replenished over relatively short timescales, while non-renewable resources such as coal, petroleum and natural gas are finite on human timescales.
Quick context: Solar, wind, hydropower and many forms of biomass are renewable energy sources.
Exam use: Competitive exams frequently ask students to classify energy sources and identify examples of renewable energy.
Exam Point: Coal is a non-renewable source of energy.
Solar System
The Solar System contains the Sun, eight planets, dwarf planets, moons, asteroids, comets and other smaller bodies. The planets in order from the Sun are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
Background: Mercury, Venus, Earth and Mars are the four inner terrestrial planets with rocky surfaces. Jupiter and Saturn are gas giants, while Uranus and Neptune are classified as ice giants.
Exam use: Questions commonly ask about the order of planets, largest planet, nearest planet to the Sun and characteristics of individual planets.
Exam Point: Jupiter is the largest planet in the Solar System.
Indian Space Science
India's space programme is led by the Indian Space Research Organisation (ISRO). Indian launch vehicles and satellites support applications such as communication, remote sensing, navigation and scientific research.
Quick context: PSLV and GSLV are important Indian launch vehicle families used for placing satellites into orbit.
Exam use: General Science and General Awareness papers may ask about ISRO, launch vehicles, satellites and Indian space missions.
Exam Point: ISRO has developed PSLV and GSLV launch vehicles.
Important Scientific Terms
| Term | Meaning |
|---|---|
| Atom | Smallest unit of an element that retains its chemical identity. |
| Molecule | Two or more atoms chemically bonded together. |
| Catalyst | A substance that changes the rate of a chemical reaction without being consumed overall. |
| Isotope | Atoms of the same element having the same atomic number but different mass numbers. |
| Neuron | A specialised cell that transmits nerve signals. |
| Hormone | A chemical messenger produced by specialised cells or glands. |
| Antibody | A protein produced by the immune system that recognises specific antigens. |
| Antigen | A substance or molecular structure recognised by the immune system and capable of triggering an immune response. |
| Osmosis | Movement of water across a selectively permeable membrane from higher water potential toward lower water potential. |
| Photosynthesis | Process through which green plants convert light energy into chemical energy stored in organic compounds. |
| Radiation | Energy transmitted through space or a medium in the form of waves or particles. |
| Gravity | Attractive interaction between masses. |
Important Comparisons
| Comparison | Key Difference |
|---|---|
| Mass vs Weight | Mass is the amount of matter; weight is the gravitational force acting on an object. |
| Speed vs Velocity | Speed is scalar; velocity has both magnitude and direction. |
| Heat vs Temperature | Heat is energy transferred because of temperature difference; temperature indicates thermal state. |
| Element vs Compound | An element contains one type of atom; a compound contains chemically combined elements. |
| Compound vs Mixture | A compound has chemically combined components in fixed proportions; a mixture is a physical combination. |
| Acid vs Base | Acids and bases show different chemical behaviour and occupy opposite sides of the pH scale. |
| Artery vs Vein | Arteries generally carry blood away from the heart; veins generally carry blood toward the heart. |
| Virus vs Bacterium | Viruses require host cells for replication; bacteria are cellular organisms. |
| Renewable vs Non-Renewable Energy | Renewable sources are naturally replenished; non-renewable resources are finite on human timescales. |
| Reflection vs Refraction | Reflection is the return of light from a surface; refraction is bending due to a change in medium and light speed. |
Exam Traps and Common Mistakes
Mass Is Not Weight
Mass is measured in kilograms, while weight is a force and is measured in newtons. Weight changes with gravitational field strength, whereas mass remains the same for the same object.
Exam Point: The SI unit of weight is newton.
Heat Is Not Temperature
Heat represents energy transferred due to a temperature difference. Temperature describes the thermal state of a body.
Exam Point: Kelvin is the SI base unit of thermodynamic temperature.
Blood Colour and Oxygen
Blood is not blue inside veins. Oxygen-rich and oxygen-poor blood are both shades of red because of haemoglobin, although their appearance differs.
Exam Point: Haemoglobin contains iron and helps transport oxygen.
Antibiotics and Viruses
Antibiotics are medicines used against bacterial infections and do not directly treat viral infections. This distinction is important in both Biology and health-related questions.
Exam Point: Antibiotics are not effective against viruses.
Planet Order
Students sometimes remember Pluto as the ninth planet. Under the current classification, Pluto is a dwarf planet, and the Solar System has eight planets.
Exam Point: Neptune is the eighth and farthest recognised planet from the Sun.
General Science One-Liners
- The SI unit of force is Newton.
- The SI unit of work and energy is Joule.
- The SI unit of power is Watt.
- The SI unit of electric current is Ampere.
- The SI unit of resistance is Ohm.
- Light can travel through a vacuum.
- Sound requires a material medium for propagation.
- Plants use chlorophyll to absorb light for photosynthesis.
- The basic structural and functional unit of life is the cell.
- Red blood cells contain haemoglobin.
- White blood cells help defend the body against infection.
- Platelets are involved in blood clotting.
- The small intestine is the main site of nutrient absorption.
- The liver produces bile.
- DNA carries hereditary information in humans.
- Vitamin C deficiency causes scurvy.
- Vitamin D deficiency can cause rickets in children.
- Iron is an important component of haemoglobin.
- Mercury is the planet nearest to the Sun.
- Jupiter is the largest planet in the Solar System.
General Science MCQs
1. What is the SI unit of force?
A. Joule
B. Newton
C. Watt
D. Pascal
Answer: B. Newton
Exam Point: Force is measured in newtons.
2. Which organ is mainly responsible for pumping blood through the human body?
A. Liver
B. Kidney
C. Heart
D. Lung
Answer: C. Heart
Exam Point: The heart pumps blood through the circulatory system.
3. Which gas is used by green plants during photosynthesis?
A. Oxygen
B. Nitrogen
C. Carbon dioxide
D. Hydrogen
Answer: C. Carbon dioxide
Exam Point: Carbon dioxide is a main raw material for photosynthesis.
4. Which of the following is a non-renewable source of energy?
A. Solar energy
B. Wind energy
C. Coal
D. Hydropower
Answer: C. Coal
Exam Point: Coal is a finite fossil fuel.
5. Which part of a plant cell contains chlorophyll?
A. Ribosome
B. Chloroplast
C. Nucleus
D. Vacuole
Answer: B. Chloroplast
Exam Point: Chloroplasts contain chlorophyll and are associated with photosynthesis.
6. Which vitamin deficiency is associated with scurvy?
A. Vitamin A
B. Vitamin B12
C. Vitamin C
D. Vitamin D
Answer: C. Vitamin C
Exam Point: Scurvy is caused by vitamin C deficiency.
7. Which planet is the largest in the Solar System?
A. Earth
B. Saturn
C. Jupiter
D. Neptune
Answer: C. Jupiter
Exam Point: Jupiter is the largest planet.
8. What is the SI unit of electric current?
A. Volt
B. Ohm
C. Watt
D. Ampere
Answer: D. Ampere
Exam Point: Electric current is measured in amperes.
9. Which blood component is mainly involved in clotting?
A. Platelets
B. Plasma
C. Red blood cells
D. Neurons
Answer: A. Platelets
Exam Point: Platelets help in blood clot formation.
10. Which phenomenon explains the bending of light when it passes from one medium to another?
A. Reflection
B. Refraction
C. Diffusion
D. Radiation
Answer: B. Refraction
Exam Point: Refraction involves a change in the direction of light due to a change in medium.
Quick Revision
| Topic | Remember This |
|---|---|
| Force | Newton |
| Work and Energy | Joule |
| Power | Watt |
| Current | Ampere |
| Resistance | Ohm |
| Life | Cell is the basic unit |
| Blood | RBCs contain haemoglobin |
| Digestion | Small intestine is the main site of nutrient absorption |
| Photosynthesis | Uses carbon dioxide, water and light energy |
| Genetics | DNA carries hereditary information |
| Acidic Solution | pH below 7 at 25°C |
| Largest Planet | Jupiter |
| Nearest Planet to Sun | Mercury |
| Indian Space Programme | ISRO |
Final Takeaway
General Science becomes easier when the basic concepts are connected with everyday observations. For competitive exams, students should give special attention to SI units, human body systems, vitamins and deficiency diseases, basic chemistry, electricity, light, sound, environment and space science.
For revision, focus on short factual pairs such as force–newton, power–watt, current–ampere, resistance–ohm, vitamin C–scurvy and vitamin D–rickets. Along with memorising facts, understanding the basic concept behind each fact can reduce confusion in multiple-choice questions.
Exam Point: Regular revision of Physics, Chemistry, Biology, Environment and Space Science can cover a large share of basic General Science questions asked in competitive examinations.
Frequently Asked Questions
1. What is General Science in competitive exams?
General Science generally covers basic concepts and facts from Physics, Chemistry, Biology, Environment and related scientific subjects. The level is usually based on school-level science and everyday applications.
2. Which subjects are included in General Science GK?
The major areas include Physics, Chemistry and Biology. Many exams also include questions related to Environment, Human Health, Space Science and everyday scientific applications.
3. What are the most important Physics topics for General Science?
Motion, force, work, energy, power, heat, light, sound, electricity, magnetism and basic units are important areas for objective examinations.
4. What are the important Biology topics for competitive exams?
Students should revise cells, human body systems, blood, nutrition, vitamins, diseases, immunity, reproduction, genetics, plant biology and ecology.
5. Which Chemistry topics should students revise?
Important areas include atoms, molecules, elements, compounds, mixtures, acids, bases, salts, metals, non-metals, chemical reactions and common chemical substances.
6. Is General Science important for SSC and Railway exams?
Yes. Basic science is commonly included in the General Awareness or General Science portions of several competitive examinations, particularly examinations conducted for SSC, Railway and similar recruitment categories.
7. How should I prepare General Science for competitive exams?
Start with school-level concepts, prepare short notes for factual information, revise important scientific terms and practise objective questions. Regular revision is useful because many questions depend on quick recall.
8. Which General Science facts should be memorised first?
Begin with SI units, human body facts, vitamins and deficiency diseases, basic chemical terms, important laws and formulas, planets, environmental terms and common scientific discoveries.
Sources referred: NCERT; NASA Science; World Health Organization (WHO); Indian Space Research Organisation (ISRO).
