GCSE CHEMISTRY EDEXCEL EXAM REVISION QUESTIONS WITH
VERIFIED SOLUTIONS LATEST 2025 UPDATE.
Element definition - ANSWER- A substance that consists entirely of atoms with the same
atomic number
Empirical formula definition - ANSWER- The simplest whole number ration of the atoms
present
Endothermic reaction definition - ANSWER- A process that absorbs energy, usually heat, from
the surroundings. (ΔH is positive)
Enthalpy change definition - ANSWER- Enthalpy of products - enthalpy of reactants
Exothermic definition - ANSWER- A process that releases energy, usually heat, to the
surroundings. (ΔH is negative)
Fossil fuel definition - ANSWER- The remains of organisms buried beneath the surface of the
earth which have been subjected to heat and pressure over millions of years.
Fuel definition - ANSWER- A substance used for producing energy
Homologous series definition - ANSWER- A family of substances with the same general
formula, with similar chemical properties and a trend in physical properties
Hydrocarbon definition - ANSWER- A compound that contains hydrogen and carbon only
Ion definition - ANSWER- An atom or group of atoms that have lost or gained electrons
,Ionic bonding definition - ANSWER- Electrons are transferred. The metal loses its outer shell
electrons to the non-metal. The ions ar held together by strong electrostatic attractions.
Isomer definition - ANSWER- Two molecules with the same molecular formula but different
arrangements of atoms
Isotope definition - ANSWER- Two forms of the same element with different numbers of
neutrons
Mass number definition - ANSWER- Total number of protons and neutrons in the nucleus of
an atom
Molar mass definition - ANSWER- The mass, in grams, of one mole of a substance
Mole definition - ANSWER- The number of atoms in 12g of carbon-12 (6x10^23 particles)
Molecular formula definition - ANSWER- Actual number of every atom present in a molecule
Molecule definition - ANSWER- Two or more atoms chemically bonded
Monomer definition - ANSWER- Small molecules that can be joined together to make
polymers
Neutralisation definition - ANSWER- The addition of an acid to an alkali, to form a neutral
solution.
Oxidation definition - ANSWER- The addition of oxygen atoms, the removal of hydrogen
atoms or the loss of electrons
, Polymer definition - ANSWER- A substance containing very long molecules consisting of
repeating units
Reduction definition - ANSWER- The removal of oxygen atoms, the addition of hydrogen
atoms or the gain of electrons
What is meant by the term 'saturated compound'? - ANSWER- All single bonds
What is a saturated solution? - ANSWER- One in which the maximum mass of a substance is
dissolved
What is meant by the term 'unsaturated compound'? - ANSWER- Contains at least one multiple
bond
What raw material does hydrogen come from? - ANSWER- Natural gas
Uses for bitumen - ANSWER- Making roads
Test fo H2 (hydrogen gas) - ANSWER- Burns with squeaky pop
Test for O2 (oxygen gas) - ANSWER- Relights glowing splint
Test for CO2 (carbon dioxide gas) - ANSWER- Turns limewater cloudy (then colourless again)
Test for Cl2 (chlorine gas) - ANSWER- Turns damp blue litmus red, then bleaches it
Test for NH3 (ammonia) - ANSWER- Turns damp red litmus paper blue
Test for NH4+ ion (ammonium ion) - ANSWER- Add NaOH (sodium hydroxide)
VERIFIED SOLUTIONS LATEST 2025 UPDATE.
Element definition - ANSWER- A substance that consists entirely of atoms with the same
atomic number
Empirical formula definition - ANSWER- The simplest whole number ration of the atoms
present
Endothermic reaction definition - ANSWER- A process that absorbs energy, usually heat, from
the surroundings. (ΔH is positive)
Enthalpy change definition - ANSWER- Enthalpy of products - enthalpy of reactants
Exothermic definition - ANSWER- A process that releases energy, usually heat, to the
surroundings. (ΔH is negative)
Fossil fuel definition - ANSWER- The remains of organisms buried beneath the surface of the
earth which have been subjected to heat and pressure over millions of years.
Fuel definition - ANSWER- A substance used for producing energy
Homologous series definition - ANSWER- A family of substances with the same general
formula, with similar chemical properties and a trend in physical properties
Hydrocarbon definition - ANSWER- A compound that contains hydrogen and carbon only
Ion definition - ANSWER- An atom or group of atoms that have lost or gained electrons
,Ionic bonding definition - ANSWER- Electrons are transferred. The metal loses its outer shell
electrons to the non-metal. The ions ar held together by strong electrostatic attractions.
Isomer definition - ANSWER- Two molecules with the same molecular formula but different
arrangements of atoms
Isotope definition - ANSWER- Two forms of the same element with different numbers of
neutrons
Mass number definition - ANSWER- Total number of protons and neutrons in the nucleus of
an atom
Molar mass definition - ANSWER- The mass, in grams, of one mole of a substance
Mole definition - ANSWER- The number of atoms in 12g of carbon-12 (6x10^23 particles)
Molecular formula definition - ANSWER- Actual number of every atom present in a molecule
Molecule definition - ANSWER- Two or more atoms chemically bonded
Monomer definition - ANSWER- Small molecules that can be joined together to make
polymers
Neutralisation definition - ANSWER- The addition of an acid to an alkali, to form a neutral
solution.
Oxidation definition - ANSWER- The addition of oxygen atoms, the removal of hydrogen
atoms or the loss of electrons
, Polymer definition - ANSWER- A substance containing very long molecules consisting of
repeating units
Reduction definition - ANSWER- The removal of oxygen atoms, the addition of hydrogen
atoms or the gain of electrons
What is meant by the term 'saturated compound'? - ANSWER- All single bonds
What is a saturated solution? - ANSWER- One in which the maximum mass of a substance is
dissolved
What is meant by the term 'unsaturated compound'? - ANSWER- Contains at least one multiple
bond
What raw material does hydrogen come from? - ANSWER- Natural gas
Uses for bitumen - ANSWER- Making roads
Test fo H2 (hydrogen gas) - ANSWER- Burns with squeaky pop
Test for O2 (oxygen gas) - ANSWER- Relights glowing splint
Test for CO2 (carbon dioxide gas) - ANSWER- Turns limewater cloudy (then colourless again)
Test for Cl2 (chlorine gas) - ANSWER- Turns damp blue litmus red, then bleaches it
Test for NH3 (ammonia) - ANSWER- Turns damp red litmus paper blue
Test for NH4+ ion (ammonium ion) - ANSWER- Add NaOH (sodium hydroxide)
