IEB Chemistry Exam Questions &
Answers 2025/2026
Mixtures - ANSWERSA combination of two or more pure substances that are not chemically
bonded together
homogeneous mixture - ANSWERSA mixture with uniform composition and the various
components of the mixture cannot be seen
heterogeneous mixture - ANSWERSA mixture that does not have uniform composition and the
various components of the mixture can be seen
Pure substances - ANSWERSAny substance that is not a mixture, including elements and
compounds
Elements - ANSWERSPure substances that cannot be broken down into simpler substances by
chemical methods
Metalloids - ANSWERSDisplay metal as well as non-metal properties
Atom - ANSWERSthe smallest component of an element having the chemical properties of the
element
Molecule - ANSWERSTwo or more atoms covalently bonded
Compound - ANSWERSA pure substance that consists of two or more elements that are
chemically binded into a single substance in a fixed ratio
, Ion - ANSWERSA charged particle
Polyatomic ion - ANSWERSan ion made of two or more atoms
Cations - ANSWERSPositively charged ions that have lost electrons
Anions - ANSWERSNegatively charged ions that have gained electrons
Diffusion - ANSWERSThe spontaneous movement of particles from a high concentration to a low
concentration
Brownian motion - ANSWERSrandom movement of particles resulting from their collision with
the fast mpving molecules in air or liquid
Kinetic molecular theory - ANSWERSA model to explain our macroscopic onservations on a
microscopic level
Sublimation - ANSWERSSubstance changes directly from a liquid to a gas
Model - ANSWERSA representation or mental picture of something we cannot directly see
Atomic number (Z) - ANSWERSThe number of protons in the nucleus of an atom
Atomic mass number (A) - ANSWERSThe number of protons and neutrons in the nucleus of the
atom
Answers 2025/2026
Mixtures - ANSWERSA combination of two or more pure substances that are not chemically
bonded together
homogeneous mixture - ANSWERSA mixture with uniform composition and the various
components of the mixture cannot be seen
heterogeneous mixture - ANSWERSA mixture that does not have uniform composition and the
various components of the mixture can be seen
Pure substances - ANSWERSAny substance that is not a mixture, including elements and
compounds
Elements - ANSWERSPure substances that cannot be broken down into simpler substances by
chemical methods
Metalloids - ANSWERSDisplay metal as well as non-metal properties
Atom - ANSWERSthe smallest component of an element having the chemical properties of the
element
Molecule - ANSWERSTwo or more atoms covalently bonded
Compound - ANSWERSA pure substance that consists of two or more elements that are
chemically binded into a single substance in a fixed ratio
, Ion - ANSWERSA charged particle
Polyatomic ion - ANSWERSan ion made of two or more atoms
Cations - ANSWERSPositively charged ions that have lost electrons
Anions - ANSWERSNegatively charged ions that have gained electrons
Diffusion - ANSWERSThe spontaneous movement of particles from a high concentration to a low
concentration
Brownian motion - ANSWERSrandom movement of particles resulting from their collision with
the fast mpving molecules in air or liquid
Kinetic molecular theory - ANSWERSA model to explain our macroscopic onservations on a
microscopic level
Sublimation - ANSWERSSubstance changes directly from a liquid to a gas
Model - ANSWERSA representation or mental picture of something we cannot directly see
Atomic number (Z) - ANSWERSThe number of protons in the nucleus of an atom
Atomic mass number (A) - ANSWERSThe number of protons and neutrons in the nucleus of the
atom
