Karnataka SSLC Science (KSEAB) key terms

A reaction in which two or more reactants join to form a single product, as when calcium oxide reacts with water to give slaked lime. The product is always one compound.

A reaction in which one compound breaks down into two or more simpler substances, usually driven by heat, light, or electricity, such as heating calcium carbonate to obtain quicklime and carbon dioxide.

Breakdown of a compound caused by heating it, for example heating lead nitrate to release brown nitrogen dioxide fumes or heating ferrous sulphate crystals until the green colour is lost.

A reaction in which a more reactive element pushes a less reactive element out of its compound, such as iron nails dipped in copper sulphate solution becoming coated with reddish-brown copper.

A reaction in which two compounds exchange ions to form two new compounds, often producing an insoluble solid; mixing sodium sulphate solution with barium chloride solution gives white barium sulphate precipitate.

A reaction in which one substance loses electrons (oxidation) while another gains them (reduction), occurring together; copper oxide heated with hydrogen giving copper and water is a standard example.

Loss of electrons by a substance, or gain of oxygen, or loss of hydrogen. In the reaction of copper with oxygen to form copper oxide, copper is oxidised and its surface turns black.

Gain of electrons by a substance, or loss of oxygen, or gain of hydrogen. Removing oxygen from copper oxide by passing hydrogen over the heated solid gives copper metal.

A symbolic equation in which the number of atoms of each element is equal on both sides, satisfying conservation of mass. Coefficients are adjusted, never subscripts, to achieve the balance.

A reaction that releases heat to the surroundings, raising the temperature of the mixture. Respiration, burning of natural gas, and the reaction of quicklime with water are familiar examples.

A reaction that absorbs heat from the surroundings, so the mixture cools. Decomposition of calcium carbonate on strong heating and photosynthesis are examples of this energy-absorbing change.

A scale from 0 to 14 expressing how acidic or basic an aqueous solution is, based on hydrogen ion concentration. Values below 7 are acidic, 7 is neutral, and above 7 is basic.

A dye or substance that changes colour according to whether a solution is acidic or basic; litmus, methyl orange, phenolphthalein, and turmeric are commonly used in the school laboratory.

The reaction of an acid with a base to give a salt and water only, for example hydrochloric acid with sodium hydroxide forming sodium chloride and water. Heat is released in this reaction.

A fixed number of water molecules chemically combined in one formula unit of a salt, as in copper sulphate pentahydrate; heating removes this water and changes the crystal colour.

Calcium sulphate hemihydrate, made by heating gypsum to about 373 K. Mixed with water it sets into a hard mass, so it is used for plastering fractured bones and for decorative mouldings.

A metal oxide that reacts with both acids and bases to form salts, showing both acidic and basic character. Aluminium oxide and zinc oxide are the standard examples in this syllabus.

An arrangement of metals in decreasing order of chemical reactivity, from potassium and sodium down to gold. Metals higher in the list displace those lower from their salt solutions.

A homogeneous mixture of a metal with one or more other elements, made to improve properties such as hardness or corrosion resistance. Brass, bronze, solder, and steel are examples.

Gradual eating away of a metal by moisture, air, or chemicals, as when iron rusts to reddish-brown hydrated iron oxide. Painting, oiling, and galvanising are common preventive methods.

The ability of an element to link its own atoms into long chains or rings. Carbon shows this property strongly, which explains the huge number of carbon compounds known.

A family of organic compounds with the same functional group in which successive members differ by one CH2 unit and about 14 u in molar mass, showing gradually changing physical properties.

An atom or group of atoms that gives an organic compound its characteristic chemical properties, such as hydroxyl in alcohols, carboxyl in carboxylic acids, and aldehyde in aldehydes.

The reaction of a carboxylic acid with an alcohol in the presence of a small amount of acid catalyst to give an ester with a pleasant fruity smell, used in perfumes and flavourings.

The alkaline hydrolysis of an ester or fat with sodium hydroxide to produce an alcohol and the sodium salt of the acid, which is soap. It is the basis of soap making.

Tiny pores, mainly on the lower surface of leaves, bordered by guard cells. They open to admit carbon dioxide for photosynthesis and allow water vapour and oxygen to diffuse out.

Loss of water vapour from the aerial parts of a plant, chiefly through stomata. It creates the pull that lifts water up the xylem and also cools the leaf surface.

Vascular tissue that conducts water and dissolved minerals upward from roots to stems and leaves. Its dead, hollow, lignified vessels and tracheids form continuous tubes.

Vascular tissue that transports soluble food materials, mainly sucrose, from leaves to other plant parts in both directions. It consists of sieve tubes, companion cells, and phloem fibres.

The movement of soluble organic food substances through the phloem from regions where they are made or stored to regions of need, such as growing tips, fruits, and roots.

A rapid, involuntary response to a stimulus in which the message travels through a reflex arc, often via the spinal cord, without waiting for the brain to decide.

The tiny gap between two neurons, or between a neuron and a muscle or gland, across which a chemical messenger diffuses so that the nerve impulse can pass onward.

The largest part of the human brain, divided into two hemispheres, concerned with thinking, memory, reasoning, and control of voluntary movements. Its surface is folded into gyri and sulci.

A form of asexual reproduction in which a single-celled organism divides into two similar daughter cells, as in Amoeba and Leishmania. It produces genetically identical offspring.

The ability of an organism to regrow a lost body part from specialised cells, as when a planarian or Hydra rebuilds its missing portion. It is not the same as reproduction in all organisms.

Asexual reproduction in plants from vegetative parts such as stems, roots, or leaves, giving rise to new plants identical to the parent. Sugarcane, potato, and Bryophyllum use this method.

The principle that the two alleles of a gene separate during gamete formation so that each gamete carries only one allele, and they pair again randomly at fertilisation.

The form of a character that appears in a heterozygous individual, masking the recessive allele. In pea plants, tallness is dominant over dwarfness in the classic cross.

The genetic constitution of an organism with respect to a particular character, described by the alleles present, such as TT, Tt, or tt for plant height.

The ratio of the speed of light in vacuum to its speed in a given medium, indicating how strongly that medium bends light. Its value is always at least one.

The bending of light as it passes obliquely from one transparent medium to another because its speed changes. The ray bends towards the normal when entering a denser medium.

A spherical mirror whose reflecting surface curves inward, converging parallel light to a real focus. It can form real or virtual images and is used in torches and vehicle headlights.

The relation 1/v minus 1/u equals 1/f for a lens, connecting image distance, object distance, and focal length. Signs are assigned using the Cartesian sign convention.

Bending of light as it travels through air layers of changing density and temperature. It makes the Sun visible a little before sunrise and causes the apparent twinkling of stars.

Splitting of white light into its component colours because different colours are refracted by different amounts, producing a spectrum through a glass prism.

Deflection of light in many directions by tiny particles in its path. Blue light scatters more than red, which is why the clear sky looks blue and sunsets look red.

The statement that the current through a metallic conductor is directly proportional to the potential difference across its ends, provided temperature stays constant. The constant ratio is the resistance.

The property of a conductor that opposes the flow of electric current, measured in ohms and equal to potential difference divided by current. It depends on length, area, material, and temperature.

The resistance of a conductor of unit length and unit cross-sectional area, a characteristic of the material itself, measured in ohm metre and varying with temperature.

The rate at which electrical energy is transferred or consumed in a circuit, equal to voltage multiplied by current and measured in watts. It also equals current squared times resistance.

Imaginary curves drawn to represent a magnetic field, whose tangent at any point gives the field direction. They run from north to south outside a magnet and never intersect each other.

A long coil of insulated wire wound in the shape of a cylinder. When current flows, the field inside is uniform and resembles that of a bar magnet, so it acts as an electromagnet.

The production of an induced current in a coil when the magnetic field linked with it changes, as when a magnet is moved towards or away from the coil.