Odisha BSE HSC General Science key terms

The tendency of an object to resist any change in its state of rest or of uniform motion in a straight line. It depends on mass, so a heavier body is harder to start or stop.

The rate of change of momentum of a body is directly proportional to the applied force and takes place in the direction of the force. It gives the relation force equals mass times acceleration.

The product of a body's mass and its velocity. It is a vector quantity measured in kilogram metre per second and shows how hard it is to stop a moving object.

Work is done when a force moves an object through a distance in the direction of the force. It equals force multiplied by displacement and is measured in joules.

The rate at which work is done or energy is transferred. It equals work divided by time and is measured in watts, where one watt is one joule per second.

At constant temperature, the current flowing through a metallic conductor is directly proportional to the potential difference across its ends, so voltage equals current times resistance.

The property of a conductor that opposes the flow of electric current through it. It is measured in ohms and depends on length, area of cross-section, material and temperature.

The bending of light when it passes from one transparent medium into another of different optical density, caused by a change in the speed of the light.

The distance between the pole of a spherical mirror, or the optical centre of a lens, and its principal focus. It is measured in centimetres or metres.

A spherical mirror whose reflecting surface curves inwards, towards the source of light. It can form real or virtual images and is used in torches and shaving mirrors.

The region around a magnet or a current-carrying wire where its magnetic force can be detected. It is described by field lines that run from north to south outside the magnet.

The number of complete oscillations or vibrations a wave makes in one second. It is measured in hertz and determines the pitch of a sound.

The combining capacity of an element, that is, the number of hydrogen atoms or equivalent atoms it can combine with or replace. It helps in writing chemical formulae correctly.

The strong electrostatic attraction between oppositely charged ions formed when one atom transfers electrons to another. It usually forms between a metal and a non-metal, as in sodium chloride.

A scale from zero to fourteen that measures how acidic or basic a solution is. Values below seven are acidic, seven is neutral and values above seven are basic.

A substance that gives hydrogen ions when dissolved in water, turns blue litmus red, and reacts with a base to form salt and water.

A substance that gives hydroxide ions in water, turns red litmus blue, and neutralises an acid to form salt and water. Soluble bases are called alkalis.

The reaction between an acid and a base that produces salt and water. The acidic and basic properties cancel each other out, and heat is usually released.

A table in which elements are arranged in order of increasing atomic number so that elements with similar properties fall in the same vertical column, called a group.

A homogeneous mixture of a metal with one or more other elements, made to improve strength, hardness or resistance to corrosion. Steel and brass are common examples.

The slow destruction of a metal by the action of air, moisture or chemicals in its surroundings. Rusting of iron is the most familiar example of this process.

One of two or more atoms of the same element that have the same number of protons but different numbers of neutrons, and hence different mass numbers.

The amount of a substance that contains as many particles as there are atoms in exactly twelve grams of carbon-12, that is, Avogadro's number of particles.

The process by which green plants make food from carbon dioxide and water using light energy trapped by chlorophyll, releasing oxygen as a by-product.

The breakdown of glucose in the presence of oxygen inside cells, releasing carbon dioxide, water and a large amount of energy stored in ATP molecules.

The movement of water molecules through a semi-permeable membrane from a region of higher water concentration to a region of lower water concentration.

Cell division in which one cell divides to form two daughter cells with the same number of chromosomes as the parent. It is used for growth and repair.

A chemical substance secreted by an endocrine gland into the blood, which travels to a target organ and controls its activity. Insulin is one familiar example.

A quick, automatic response to a stimulus that does not require thinking, such as pulling the hand away from a hot object. It is controlled by the spinal cord.

A segment of DNA on a chromosome that carries the instructions for a particular inherited feature or for making a specific protein in the body.

A protein that speeds up a chemical reaction in a living cell without being used up itself. Each enzyme acts on one specific substrate.

The plant tissue that carries water and dissolved minerals upwards from the roots to the leaves. Its vessels are made of dead, hollow cells.

Giving a person a weakened or killed form of a pathogen, or its product, so that the body makes antibodies and becomes protected against that disease.

A self-contained unit in which living organisms interact with one another and with their non-living surroundings, such as a pond, a grassland or a forest.

A series of organisms through which energy passes as one is eaten by another, starting with a producer and ending with a top consumer.

The variety of living things found in a place, including the different species, their genetic differences and the ecosystems they together form.

The trapping of heat in the atmosphere by gases such as carbon dioxide and methane, which let sunlight in but absorb the infrared radiation given out by the Earth.

A layer of ozone gas in the upper atmosphere that absorbs most of the Sun's harmful ultraviolet radiation and so protects life on Earth.

Development that meets the needs of people today without using up resources or damaging the environment in ways that make life harder for future generations.

Describes waste that can be broken down by the action of bacteria and other micro-organisms into harmless simple substances within a reasonable time.