General Science GK: Physics, Chemistry and Biology MCQs

General Science GK helps competitive-exam students understand the scientific principles behind everyday life, the human body, common materials, energy and the environment. Questions often test basic concepts such as Newton's laws, acids and bases, cell structure, vitamins, electricity and the properties of matter.

This General Science study guide brings together key Physics, Chemistry and Biology facts with simple explanations, common exam traps and practice MCQs. The concepts are suitable for general competitive-exam revision, while the depth required may vary by exam and syllabus.

Last Updated: 26 October 2026, 03:06 PM IST | Reviewed by Vijay Sah

Quick Facts

Topic	Fact
Physics	Study of matter, energy, motion, forces and their interactions
Chemistry	Study of substances, their properties, composition and reactions
Biology	Study of living organisms and life processes
SI unit of force	Newton (N)
SI unit of power	Watt (W)
Neutral pH at about 25°C	7
Basic unit of life	Cell
Oxygen transport in human blood	Primarily by haemoglobin in red blood cells
Genetic material in most organisms	DNA
Photosynthesis	Process by which green plants use light energy to make food from carbon dioxide and water

Physics GK: Motion, Force, Light and Energy

Physics explains how objects move, how forces act, how energy changes form and how light, sound and electricity behave. Many exam questions focus on the meaning of a physical quantity, its SI unit or a familiar application.

Motion and Newton's laws

Speed: Distance travelled per unit time. Its SI unit is metre per second (m/s).
Velocity: Displacement per unit time in a specified direction. It is a vector quantity.
Acceleration: Rate of change of velocity with time. Its SI unit is metre per second squared (m/s²).
Newton's first law: An object remains at rest or continues in uniform motion in a straight line unless acted upon by a net external force.
Newton's second law: The net force is related to the rate of change of momentum. For constant mass, it is expressed as F = ma.
Newton's third law: Forces between interacting bodies occur in equal and opposite pairs, acting on different bodies.

Inertia is the tendency of an object to resist a change in its state of motion. A passenger may move forward when a moving bus stops suddenly because the passenger's body tends to continue moving.

Exam Trap: Action and reaction forces do not cancel each other on one object because they act on different objects.

Work, energy and power

Work: In basic mechanics, work is done when a force causes displacement. For a constant force, work depends on the force component along the displacement.
Kinetic energy: Energy associated with motion. For an object of mass m moving at speed v, kinetic energy is ½mv².
Potential energy: Energy associated with position or configuration, such as gravitational potential energy near Earth's surface.
Power: Rate of doing work or transferring energy. Its SI unit is watt.
Conservation of energy: Energy is not created or destroyed in an isolated system; it changes from one form to another.

The SI unit of work and energy is the joule (J). Power is measured in watts, where one watt equals one joule per second.

Heat, temperature and sound

Heat: Energy transferred because of a temperature difference.
Temperature: A measure related to the thermal state of a body; it is not the same as the total heat energy it contains.
Conduction: Transfer of thermal energy through a material without bulk movement of the material as a whole.
Convection: Heat transfer involving the bulk movement of a fluid, such as a liquid or gas.
Radiation: Energy transfer by electromagnetic waves; it does not require a material medium.
Sound: A mechanical wave that requires a medium to travel. Sound cannot travel through a vacuum.

Exam Point: Heat from the Sun reaches Earth through radiation, while sound needs a material medium for propagation.

Light, mirrors and lenses

Reflection: The bouncing back of light from a surface.
Refraction: Change in the direction of light when it passes between media because its speed changes.
Convex lens: A converging lens for light rays parallel to its principal axis.
Concave lens: A diverging lens for light rays parallel to its principal axis.
Dispersion: Separation of white light into its component colours, as can occur when light passes through a prism.

A plane mirror forms a virtual, upright image of the same size as the object. The image appears as far behind the mirror as the object is in front of it.

Electricity and magnetism

Electric current: Rate of flow of electric charge. Its SI unit is ampere (A).
Potential difference: Work done per unit charge between two points. Its SI unit is volt (V).
Resistance: Opposition to electric current. Its SI unit is ohm (Ω).
Ohm's law: For a conductor under constant physical conditions, voltage is proportional to current; V = IR.
Magnetic field: The region in which magnetic forces can be experienced.
Electromagnet: A magnet produced by electric current, commonly using a coil and a magnetic core.

Electrical energy can be converted into light, heat, sound or motion. A fuse or suitable circuit breaker helps protect a circuit against excessive current, while earthing provides a path for fault current in properly designed electrical installations.

Chemistry GK: Matter, Elements and Reactions

Chemistry studies the composition, structure and properties of substances, along with the changes they undergo. Exam questions commonly cover elements, compounds, mixtures, acids, bases, metals and everyday chemical reactions.

Elements, compounds and mixtures

Element: A pure substance made of one type of atom, such as iron, oxygen or copper.
Compound: A substance formed when two or more elements combine chemically in a fixed proportion, such as water (H₂O).
Mixture: A physical combination of substances whose components can generally be separated by physical methods.
Atom: The smallest unit of an element that retains its chemical identity.
Molecule: A group of two or more atoms chemically bonded together. Some molecules contain atoms of the same element, such as O₂.

Air is a mixture of gases. Water is a compound because hydrogen and oxygen are chemically combined in a fixed ratio. This difference is frequently used to test whether a student can distinguish a mixture from a compound.

Acids, bases and salts

Acids: In aqueous solution, acids increase the concentration of hydrogen ions, represented more accurately as hydronium ions in water.
Bases: Many bases produce hydroxide ions in water or accept protons, depending on the definition used.
Neutralisation: A reaction between an acid and a base that commonly forms salt and water.
pH: A scale used to express acidity or basicity. At about 25°C, pH 7 is neutral in the usual introductory context.
Indicators: Substances that change colour over particular pH ranges or in response to acidic and basic conditions.

Blue litmus generally turns red in an acidic solution, while red litmus generally turns blue in a basic solution. The pH of a solution depends on its chemical composition and conditions; the number 7 is not a universal neutral pH at every temperature.

Metals, non-metals and common materials

Metals: Many metals conduct heat and electricity well and can be shaped. These are general trends, not rules without exceptions.
Non-metals: Many non-metals are poor electrical conductors, although graphite is a well-known exception.
Rusting: Iron corrodes in the presence of oxygen and moisture, forming hydrated iron oxides and related corrosion products.
Alloy: A material made by combining an element with one or more other elements, at least one of which is usually a metal.
Stainless steel: An iron-based alloy containing chromium, with other elements depending on the grade, that resists corrosion.

Galvanisation protects iron or steel by applying a zinc coating. Painting can also limit corrosion by reducing contact with air and moisture, provided the protective layer remains intact.

Atoms, periodic table and chemical reactions

Proton: Positively charged subatomic particle found in the atomic nucleus.
Neutron: Electrically neutral subatomic particle found in the nucleus of most atoms.
Electron: Negatively charged particle found in atomic orbitals.
Atomic number: Number of protons in the nucleus of an atom.
Mass number: Total number of protons and neutrons in a particular nucleus.
Oxidation: In modern redox terminology, loss of electrons; it can also be described in terms of oxygen gain or hydrogen loss in common reactions.
Reduction: Gain of electrons; in common reactions it can also involve oxygen loss or hydrogen gain.

The periodic table arranges elements by increasing atomic number. Elements in the same group often have similar chemical properties because of similarities in their outer-electron arrangements.

Exam Trap: Atomic number counts protons, not neutrons. In a neutral atom, the number of electrons equals the number of protons.

Biology GK: Cells, Plants and Living Organisms

Biology examines living organisms, from microscopic cells to complex plants and animals. Basic questions often ask about cell parts, plant nutrition, respiration, reproduction and inheritance.

Cell structure and function

Cell: The basic structural and functional unit of life.
Nucleus: Contains most of the genetic material in a typical eukaryotic cell and helps regulate cellular activities.
Mitochondria: Organelles involved in cellular respiration and ATP production.
Ribosomes: Structures where proteins are made.
Cell membrane: A selectively permeable boundary that regulates the movement of substances into and out of the cell.
Cell wall: A supporting outer structure found in plants, fungi and many other organisms, but not in animal cells.
Chloroplasts: Organelles in plants and algae that carry out photosynthesis.

Plant cells typically have a cell wall, chloroplasts in photosynthetic tissues and a large central vacuole. Animal cells lack a cell wall and chloroplasts.

Photosynthesis and respiration

Photosynthesis uses light energy to convert carbon dioxide and water into energy-rich organic compounds, releasing oxygen in oxygenic photosynthesis. Chlorophyll helps capture light energy.

Cellular respiration releases usable energy from organic molecules. Aerobic respiration uses oxygen as the final electron acceptor in the main respiratory pathway and produces carbon dioxide and water from glucose under complete oxidation.

Photosynthesis stores energy in chemical compounds, while respiration makes energy available for cellular processes. Plants carry out respiration as well as photosynthesis; respiration does not stop at night.

Genes, DNA and heredity

DNA: Deoxyribonucleic acid, the hereditary material in most organisms.
Gene: A segment of genetic material that contributes to a functional product or helps regulate biological functions.
Chromosome: A structure made of DNA and associated proteins that carries genetic information in cells.
Heredity: Transmission of genetic information from parents to offspring.
Variation: Differences among individuals of the same species, arising from genetic and environmental factors.

Genes influence inherited characteristics, but many traits also depend on environmental conditions and interactions among multiple genes. Not every human characteristic is controlled by a single gene.

Exam Angle: Questions may ask for the full form of DNA, the role of chromosomes or the difference between a gene and a cell organelle.

Human Body: Organs, Blood and Vitamins

Human physiology explains how organ systems work together to maintain the body's functions. The following facts are useful for basic Biology and general science revision.

Heart: Muscular organ that pumps blood through the circulatory system.
Red blood cells: Carry most blood oxygen using haemoglobin.
White blood cells: Participate in immune defence.
Platelets: Help blood clotting.
Lungs: Exchange oxygen and carbon dioxide between air and blood.
Kidneys: Filter blood, regulate water and electrolyte balance, and help remove metabolic waste through urine formation.
Liver: Processes nutrients, produces bile and performs many metabolic functions.
Insulin: Hormone produced by pancreatic beta cells that helps regulate blood glucose.
Neuron: A specialised cell that transmits information through electrical and chemical signalling.

Vitamins and deficiency conditions

Vitamin	Main role or association
Vitamin A	Vision, epithelial tissues and immune function; deficiency can cause night blindness
Vitamin B1	Energy metabolism and nerve function; deficiency can cause beriberi
Vitamin B12	Red blood cell formation and nervous system function; deficiency can cause megaloblastic anaemia and neurological problems
Vitamin C	Collagen formation and wound healing; deficiency causes scurvy
Vitamin D	Calcium and phosphate regulation; deficiency can cause rickets in children
Vitamin K	Normal blood clotting; deficiency can impair clotting

A balanced diet supplies essential nutrients, but the amount required varies with age, health and other factors. Vitamin deficiency symptoms can have more than one cause, so a symptom alone does not establish a diagnosis.

Environment and Everyday Science

Environmental science connects biology, chemistry and physics to ecosystems, natural resources and pollution.

Ecosystem: A community of organisms interacting with one another and with their physical environment.
Food chain: A sequence showing how energy and nutrients move between organisms through feeding relationships.
Decomposers: Organisms such as many fungi and bacteria that break down dead organic matter and recycle nutrients.
Greenhouse effect: Warming caused when greenhouse gases absorb and re-emit infrared radiation in the atmosphere.
Ozone layer: A region of the stratosphere with relatively high ozone concentration that absorbs much of the Sun's harmful ultraviolet radiation.
Biodegradable waste: Waste that can be broken down by biological processes under suitable conditions.
Renewable energy: Energy from sources replenished naturally on a human timescale, such as sunlight and wind.

The natural greenhouse effect makes Earth warmer than it would otherwise be. Human activities that increase greenhouse-gas concentrations strengthen this effect and contribute to global warming.

Ozone depletion and climate change are different environmental problems. Some substances have contributed to ozone depletion, while greenhouse gases such as carbon dioxide and methane contribute to warming through their effects on the Earth's energy balance.

Common General Science Exam Traps

Mass and weight are different: mass measures matter, while weight is the gravitational force on an object.
Heat is energy transfer caused by a temperature difference; temperature is a different physical quantity.
Sound needs a medium, while electromagnetic radiation can travel through a vacuum.
Graphite conducts electricity even though it is a form of carbon classified as a non-metal.
A neutral atom has equal numbers of protons and electrons; the neutron count can vary between isotopes.
Plants respire as well as photosynthesise.
Red blood cells carry most oxygen using haemoglobin; white blood cells are involved in immune defence.
Vitamin C deficiency is associated with scurvy; vitamin D deficiency can cause rickets in children.
The ozone layer absorbs much harmful ultraviolet radiation; the greenhouse effect concerns the absorption and re-emission of infrared radiation.
In a series circuit, the same current passes through each component; in a parallel circuit, branches share the same potential difference in an ideal circuit.

General Science One-Liners

The SI unit of force is the newton.
The SI unit of energy is the joule.
The SI unit of electric current is the ampere.
Water has the chemical formula H₂O.
The atomic number equals the number of protons in the nucleus.
Ribosomes are the sites of protein synthesis.
Chlorophyll helps capture light energy for photosynthesis.
DNA stands for deoxyribonucleic acid.
Haemoglobin helps transport oxygen in red blood cells.
The kidneys help regulate fluid balance and form urine.

General Science GK MCQs

Q1. What is the SI unit of force?
A. Joule
B. Watt
C. Newton
D. Pascal
Correct Answer: C. Newton

Q2. Which law explains why a passenger tends to move forward when a moving bus stops suddenly?
A. Newton's first law
B. Newton's third law only
C. Law of reflection
D. Ohm's law
Correct Answer: A. Newton's first law

Q3. Which of the following is a compound?
A. Air
B. Brass
C. Soil
D. Water
Correct Answer: D. Water

Q4. Which particle determines the atomic number of an element?
A. Neutron
B. Proton
C. Photon
D. Molecule
Correct Answer: B. Proton

Q5. Which cell structure is the main site of protein synthesis?
A. Ribosome
B. Cell wall
C. Vacuole
D. Chloroplast only
Correct Answer: A. Ribosome

Q6. Which vitamin deficiency is associated with scurvy?
A. Vitamin A
B. Vitamin D
C. Vitamin C
D. Vitamin K
Correct Answer: C. Vitamin C

Q7. Which process allows heat to travel from the Sun to Earth through space?
A. Conduction
B. Convection
C. Evaporation
D. Radiation
Correct Answer: D. Radiation

Q8. Which statement about plants is correct?
A. Plants do not respire
B. Plants carry out respiration as well as photosynthesis
C. Plants use only oxygen to make food in photosynthesis
D. All plant cells contain chloroplasts
Correct Answer: B. Plants carry out respiration as well as photosynthesis

Q9. What does Ohm's law express for a conductor under constant physical conditions?
A. V = IR
B. P = F/A
C. E = mc²
D. W = mg
Correct Answer: A. V = IR

Q10. Which atmospheric region contains the ozone layer that absorbs much of the Sun's harmful ultraviolet radiation?
A. Troposphere only
B. Earth's core
C. Stratosphere
D. Ocean floor
Correct Answer: C. Stratosphere

Frequently Asked Questions

What are the main branches of General Science?

The main branches covered in basic General Science are Physics, Chemistry and Biology. Environmental science also draws on concepts from all three.

What is the difference between mass and weight?

Mass measures the amount of matter and is measured in kilograms. Weight is the gravitational force acting on an object and is measured in newtons.

Why can sound not travel through a vacuum?

Sound is a mechanical wave that transfers energy through vibrations of particles in a medium. A vacuum has no material medium to carry those vibrations.

What is the difference between an element and a compound?

An element contains one type of atom. A compound contains two or more elements chemically combined in a fixed proportion.

Do plants respire at night?

Yes. Plant cells carry out cellular respiration during both day and night. Photosynthesis requires a suitable light source, so it does not continue in darkness.

Which sources are useful for General Science revision?

NCERT science textbooks provide foundational explanations of Physics, Chemistry and Biology. Students should also check their examination's official syllabus to decide which topics and level of detail to study.

Sources referred: NCERT Class X Science textbook, NCERT Science textbook resources, NCERT CIET Class X Science.