NCERT Class X Science - Key Concepts and Terminology

Comprehensive vocabulary flashcards covering foundational terminology, definitions, and principles across Class 10 NCERT Science.

Combination Reaction

A chemical reaction in which a single product is formed from two or more reactants.

Exothermic Reaction

A chemical reaction in which heat is released along with the formation of products.

Endothermic Reaction

A reaction in which energy is absorbed from the surroundings in the form of heat, light, or electricity to break down the reactants.

Displacement Reaction

A chemical reaction in which a more reactive element displaces or removes another element from its compound.

Double Displacement Reaction

A reaction in which there is an exchange of ions between the reactants to form new compounds.

Precipitation Reaction

Any chemical reaction that produces an insoluble solid called a precipitate.

Corrosion

The gradual deterioration of a metal when it is attacked by substances around it, such as moisture and acids.

Rancidity

The condition produced by aerial oxidation of fats and oils in food, marked by an unpleasant smell and taste.

Olfactory Indicator

A substance whose odor changes in acidic or basic media (such as onion, vanilla essence, or clove oil).

Neutralization Reaction

The chemical reaction between an acid and a base to produce salt and water.

pH Scale

A scale for measuring hydrogen ion concentration in a solution, where values less than $7$ indicate an acidic solution, $7$ is neutral, and values up to $14$ indicate an alkaline solution.

Water of Crystallisation

The fixed number of water molecules chemically attached to each formula unit of a salt in its crystalline state.

Malleability

The property of metals that allows them to be beaten into thin sheets without breaking.

Ductility

The ability of a metal to be drawn into thin wires.

Amphoteric Oxide

A metal oxide that reacts with both acids and bases to produce salt and water, such as aluminium oxide and zinc oxide.

Aqua Regia

A freshly prepared, highly corrosive, and fuming mixture of concentrated hydrochloric acid and concentrated nitric acid in a ratio of $3:1$, capable of dissolving gold and platinum.

Roasting

The heating of sulfide ores strongly in the presence of excess air to convert them into metal oxides.

Calcination

The heating of carbonate ores strongly in limited air to convert them into metal oxides.

Alloy

A homogeneous mixture of two or more metals, or a metal and a non-metal, prepared to enhance properties such as strength and resistance to corrosion.

Catenation

The unique ability of carbon atoms to form covalent bonds with other carbon atoms, giving rise to long chains, branched chains, or cyclic structures.

Homologous Series

A family of organic compounds having the same functional group and similar chemical properties, in which successive members differ by a $-\text{CH}_2-$ unit and $14\,u$ in molecular mass.

Saponification

The alkaline hydrolysis of an ester using a base such as sodium hydroxide to yield an alcohol and the sodium salt of a carboxylic acid (soap).

Micelle

An aggregate of soap or detergent molecules formed in water, where the hydrophobic carbon tails cluster in the center around oil and the ionic hydrophilic heads face outward into the water.

Modern Periodic Law

The principle stating that the physical and chemical properties of elements are a periodic function of their atomic numbers.

Photosynthesis

The biological process by which green plants and autotrophs convert carbon dioxide and water into carbohydrates in the presence of sunlight and chlorophyll.

Stomata

Microscopic pores found on the surface of leaves through which gaseous exchange and transpiration occur, regulated by guard cells.

Peristaltic Movements

Rhythmic, wave-like muscular contractions along the lining of the alimentary canal that push food forward.

Nephron

The microscopic structural and functional filtration unit of the kidney, consisting of a Bowman's capsule, a glomerulus, and a long tubular segment.

Translocation

The transport of soluble products of photosynthesis through the phloem tissue from leaves to storage and growing parts of a plant.

Synapse

The microscopic gap between the axon terminal of one neuron and the dendrite of the next, where electrical impulses are converted into chemical signals for transmission.

Reflex Arc

The neuronal pathway that mediates a reflex action, directly connecting receptor sensory neurons to motor neurons through the spinal cord for rapid, automatic responses.

Auxin

A plant hormone synthesized at the shoot tip that promotes cell elongation and mediates phototropic responses by accumulating on the shaded side of the stem.

Placenta

A specialised disc-shaped vascular tissue embedded in the uterine wall that provides a large surface area for glucose, oxygen, and waste exchange between mother and developing embryo.

Homologous Organs

Organs in different species that share a similar basic anatomical structure and developmental origin, indicating shared evolutionary ancestry, though they may serve different functions.

Analogous Organs

Organs in different organisms that perform similar functions and look superficially alike, but possess different basic structural designs and origins.

Speciation

The evolutionary process by which new, distinct biological species arise from preexisting populations due to factors like genetic drift, natural selection, and geographical isolation.

Fossils

The preserved remains, impressions, or traces of organisms that lived in the remote geological past.

Refractive Index

The ratio of the speed of light in vacuum (or air) to the speed of light in a given transparent medium, representing its light-bending ability.

Snell's Law

The law of refraction stating that the ratio of the sine of the angle of incidence ($\sin(i)$) to the sine of the angle of refraction ($\sin(r)$) is constant for light of a given color and a given pair of media.

Power of a Lens

The degree of convergence or divergence of light rays achieved by a lens, defined as the reciprocal of its focal length in meters ($P = \frac{1}{f}$) and expressed in dioptres ($\text{D}$).

Power of Accommodation

The ability of the human eye lens to adjust its focal length using ciliary muscles to clearly view objects at varying distances.

Myopia

A vision defect (near-sightedness) where distant objects cannot be seen clearly because the image is focused in front of the retina; corrected using a concave lens.

Hypermetropia

A vision defect (far-sightedness) where nearby objects cannot be seen clearly because light rays are focused behind the retina; corrected using a convex lens.

Tyndall Effect

The phenomenon of scattering of light by colloidal particles in a suspension or medium, making the trajectory of the light beam visible.

Electric Potential Difference

The amount of work done in moving a unit positive charge from one point to another in an electric circuit ($V = \frac{W}{Q}$), measured in volts ($\text{V}$).

Ohm's Law

The relationship stating that the electric current ($I$) flowing through a metallic conductor is directly proportional to the potential difference ($V$) across its ends, provided its temperature remains constant ($V = I \times R$).

Joule's Law of Heating

The law stating that the heat produced in a resistor is directly proportional to the square of the current, the resistance, and the time during which current flows ($H = I^2 \times R \times t$).

Right-Hand Thumb Rule

A rule stating that if you hold a current-carrying straight conductor in your right hand with the thumb pointing in the direction of the current, your curled fingers encircle the wire in the direction of the magnetic field lines.

Solenoid

A coil consisting of many circular turns of insulated copper wire wrapped closely in the shape of a cylinder, which generates a magnetic field identical to that of a bar magnet when energized.

Fleming's Left-Hand Rule

A rule stating that if the thumb, forefinger, and middle finger of the left hand are stretched mutually perpendicular, the forefinger indicates the magnetic field, the middle finger indicates the current, and the thumb indicates the direction of motion or mechanical force.

Electromagnetic Induction

The generation of an induced electric current in a circuit caused by relative motion between a conductor and a magnetic field or by a changing magnetic flux.

Trophic Level

Each distinct feeding stage or step in a food chain through which energy and matter are transferred in an ecosystem.

Biological Magnification

The progressive increase in the concentration of non-biodegradable toxic chemicals (such as pesticides) at successively higher trophic levels in a food chain.

Sustainable Development

Economic and social development that fulfills the current basic human needs while preserving natural resources and ecosystems for future generations.