Important Science Terms for UPSC Preparation

Important Science terms

Important Science Terms for UPSC Preparation

Science is the most integral part of our life. Everything around us is science. From the tiniest bit of our earth to complex life forms, science is present everywhere. We learn and understand scientific concepts more through our experiences than books. However, that knowledge is not conveyable without proper vocabulary. In UPSC, it is important to include appropriate terminology to express yourself efficiently. That’s why it is essential to learn important science terms for UPSC Preparation.

IAS ke Funde understands the needs of IAS aspirants very well. That’s why we’ve brought you a list of the most important terms used in various fields of science. Read the full list of important science terms for UPSC Preparation and expand your vocabulary. 


  • Energy

Energy is the most essential element in science. Every small entity has energy, and this energy is running the whole universe. In layman terms, energy is the strength or capacity to perform work. There are different types of energies that are responsible for every big or small event happening in the universe. In Einstein’s words, Energy can never be destroyed. However, it could be converted from one form to another. 

  • Fusion and Fission

Fusion and Fission are the ultra-microscopic processes that happen inside the atoms.  Nuclear Fusion is the process that occurs when the nuclei of two separate atoms join to form a single atom. The stars like our Sun work because of nuclear fusion. The energy in the sun is a result of the nuclear fusion between the hydrogen and helium nuclei.

In Nuclear Fission, the nucleus of an atom splits itself into smaller nuclei. This process generates a lot of heat and energy. The atom bombs dropped on Hiroshima and Nagasaki during World War – II worked on the principle of nuclear fission. The atom bombs generate an enormous amount of energy when fission of uranium atom happens. 

  • Force

Force is any physical interaction that changes the state of an object. Without the application of force, a body will stay in its state of rest or motion because of inertia. 

  • Inertia

In simple words, Inertia is the tendency of any object to remain in the state of motion or rest until an external force is applied. For instance, a ball will stay in rest until someone pushes it. Similarly, it will keep rolling unless friction or some other force stops it.

  • Friction

Friction is the force exerted by two surfaces on each other when they are in motion. A rolling ball stops on its own after a while because the ground is exerting the force of friction on the ball. The surface of the ball and ground exert equal force on each other. When this force overcomes the kinetic energy of the body, the motion of the body comes to rest. 

  • Kinetic Energy 

When force is applied to a body, Kinetic Energy is the work required to produce motion. There will be no motion in the object if the force required is less than the Kinetic Energy. 

  • Potential Energy

Contrary to Kinetic Energy, Potential Energy is the stored energy in the body when it is at rest. When the object is put in motion, it’s potential energy gets converted to kinetic energy.

  • Strain

The strain is the change in the structure of a body when stress is applied to it.

  • Stress

Stress is the physical measure of the amount of force applied to a body.

  • Torque 

In general, Torque is the force required to put an object in a rolling motion. The force applied on a rotating object is calculated in Torque. In general, you can say that torque is the turning effect on a body. 

  • Viscosity 

It is a general perception that Viscosity is the level of density of a liquid, or friction between the surface of the liquid and some other surface. However, the truth is that Viscosity the level of friction between the atoms of the liquid. Simply said, Viscosity is the internal friction of a fluid.


  • Atom

The smallest fundamental unit of matter is Atom. Atom can be further divided into electrons, protons, and neutrons. But the central unit that is responsible for the construction of matter is Atom. 

  • Electrons 

An electron is a subatomic unit that has a negative charge.

  • Protons 

Protons are the subatomic particles carrying a positive charge.

  • Neutrons 

Atomic particles that carry neutral or no charge are known as neutrons.

  • Nucleus 

The nucleus is the centre of every atom that contains Protons and Neutrons.

  • Bond

In general words, a Bond is a link that chemically connects the atoms together. Bonds are responsible for the structure of the matter. The stronger the bond, the more robust the matter is. 

  • Element 

When similar atoms combine, an element is formed. For instance, the oxygen element is formed when atoms oxygen bond together. An element always has atoms that have the same atomic number.

  • Atomic number 

If you take a look at the periodic table, you will notice a number above the symbol of the element. This number is the atomic number of the element is used to denote the number of protons in its atom. The number above the symbol of Oxygen is 8. That means, the atomic number and number of protons in an oxygen atom is 8. Likewise, hydrogen has 2 protons. Therefore, the atomic number of hydrogen is 2. 

  • Atomic weight 

Atomic weight is present on the bottom of the Atomic Symbol in the periodic table and represents the average weight of the atom. It takes into consideration the most stable form, at which an element is present. For instance, oxygen is present in the atmosphere as O2. Thus, the atomic weight of oxygen is calculated by multiplying the atomic number with the number of atoms that form the molecule of oxygen. That is 8×2 = 16.

  • Molecule 

A molecule is the most stable form of an element or matter. A molecule can be made by combining atoms having the same or different atomic numbers. For example, the stable oxygen is found as O2, which is formed by a combination of two oxygen atoms. Whereas, water is found as H2O; which has two atoms of hydrogen and one atom of oxygen.

  • pH Scale 

The pH scale is a standard to measure the level of acidity in a substance. In technical terms, the pH scale measures the concentration of hydrogen ions in the substance. The neutral value in pH scale is 7. If a chemical has a pH higher than 7, it has an acid nature. If the pH is lower than, the chemical has a basic nature. Neutral chemicals, like salts and pure water, have a pH value of 7.

  • Boiling Point 

The boiling point of a liquid is the exact temperature at which its transition to the gaseous state starts. Water has a boiling point of 100 °C. 

  • Evaporation 

When a liquid starts to turn to gas before reaching its boiling point, it turns into vapours. The name of this phenomenon is Evaporation.

  • Absolute Zero

Absolute Zero is a theoretical temperature. It is not possible to achieve this temperature practically because no process is 100% efficient. Absolute Zero is the lowest temperature possible that can cease all the molecular activity.

  • Freezing Point 

Freezing Point is the temperature at which a liquid starts to solidify. For example, water starts to freeze at 0 °C. 

  • Catalyst 

A substance that helps in increasing the rate of a chemical reaction is called a catalyst. A catalyst speeds up a reaction by reducing the activation energy required to start the reaction. 

Important Science terms


  • Enzymes 

Like catalysts, Enzymes also speed up the reactions. But only in biological processes. In the body, enzymes are responsible for specific vital functions. For example, gastric enzymes like pepsin break down the proteins in our food into smaller bits. Therefore, it is safe to say that enzymes are biological catalysts. 

  • Evolution 

Evolution is the natural process of adaptation to the surroundings. As the environment changes the future generations of every species evolve themselves to survive more efficiently. For example, humans have evolved throughout history to become more intelligent and efficient at surviving by learning new things. 

  • Natural Selection

Natural Selection is the process that takes place during evolution to exclude the less desirable traits for survival. This process is also described as “survival of the fittest.” As the changes in the environment occur, the individuals with unfitting characteristics are unable to survive, and thus, only survivable traits are present in future generations. This process is the key to learn how species evolve. 

  • Habitat 

Habitat is a suitable environment in which a particular species survives. For instance, the amazonian rain forests are habitat to 10% of all the species that have been discovered so far.

  • Invertebrate 

All the species that lack the backbone are known as Invertebrates. Worms, spiders, molluscs, crustaceans, and insects are an example of invertebrates.

  • Vertebrate 

Animals with backbones belong to the Vertebrates classification. Most mammals, birds, amphibians, reptiles are vertebrates.

  • Pathogen 

A pathogen is a disease-causing agent like bacteria, viruses, etc.

Laboratory Terms

  • Hypothesis 

A hypothesis is the starting point of an experiment. All the steps and the possible outcomes from an experiment are a part of the hypothesis. A strong hypothesis contains the observations from previous experiments, steps and processes required, and an outcome.

  • Procedure 

The procedure is the method of performing an experiment. It contains all the steps that must be followed to get the desired result.

  • Data 

Data is the information that is gathered after or during an experiment. Collection of data gives us results to prove the validity of the hypothesis.

  • Control and Variable

The constant factor in an experiment is Control, and the factor that keeps changing is Variable. For example, if you are trying to dilute acid to 50% of the level of its concentration, the amount of acid will be constant while the amount of diluting agent will keep changing. In this case, acid is controlled, whereas, the diluting agent is variable.

Qualitative Observation vs Quantitative Observation

In Qualitative Observation, only words are used to describe the experiment and its outcome. Quantitative Observation includes proper numbers and figures for every step performed during the experiment.

These were the most important science terms for UPSC preparation. You can use these words in your answers of the mains examination to impress the examiner with your unique vocabulary. Moreover, it is important to learn these important science terms for UPSC preparation to express your knowledge in a proper way. Without a good vocabulary, all your knowledge is waste. You can suggest us more such terms by leaving a comment. We’ll try to add as many words as possible to make it an indispensable part of your preparation for UPSC CSE.

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