AQA A-LEVEL CHEMISTRY ACTUAL TEST
PAPER 2026 QUESTIONS WITH
SOLUTIONS GRADED A+
◉ 4 main characteristics of Transition metals. Answer: complex
formation, formation of coloured ions, variable oxidation state,
catalytic activity
◉ what is a complex. Answer: a central metal ion surrounded by
ligands
◉ what is a ligand. Answer: An atom, ion or molecule which can
donate a lone electron pair
◉ what is a coordinate bond. Answer: Co-ordinate bonding is when
the shared pair of electrons in the covalent bond come from only one
of the bonding atoms
◉ what is coordination number. Answer: The number of co-ordinate
bonds formed to a central metal ion
◉ why is carbon monoxide toxic. Answer: CO is toxic to humans as
CO can from a strong coordinate bond with haemoglobin. This is a
,stronger bond than that made with oxygen and so it replaces the
oxygen attaching to the haemoglobin
◉ what is the chelate effect. Answer: The substitution of
monodentate ligand with a bidentate or a multidentate ligand leads
to a more stable complex. This chelate effect can be explained in
terms of a positive entropy change in these reactions as more
molecules of products than reactants
◉ type of isomerism shown in square planar/octahedral complexes.
Answer: E-Z
◉ isomerism shown only in octahedral complexes. Answer:
Complexes with 3 bidentate ligands can form two optical isomers
(non-superimposable mirror images)
◉ how do transition metals show colour. Answer: Colour arises from
electronic transitions from the ground state to excited states:
between different d orbitals.
A portion of visible light is absorbed to promote d electrons to higher
energy levels. The light that is not absorbed is transmitted to give the
substance colour.
◉ what is the equation which links the colour and frequency of the
light absorbed with the energy difference between the split d
orbitals. Answer: E = hv.
,v = frequency of light absorbed (unit s-1 or Hz) h= Planck's constant
6.63 × 10-34 (J s)
E = energy difference between split orbitals (J)
◉ how can you change colour of transition metals. Answer:
Changing a ligand or changing the coordination number will alter the
energy split between the d- orbitals, changing E and hence change
the frequency of light absorbed
◉ describe the method of spectroscopy. Answer: •Add an
appropriate ligand to intensify colour •Make up solutions of known
concentration (dilution series)
•Measure absorption or transmission
•Plot graph of absorption vs concentration •Measure absorption of
unknown and compare
◉ general trend of variable oxidation states. Answer: - Relative
stability of +2 state with respect to +3 state increases across the
period
- Compounds with high oxidation states tend to be oxidising agents
e.g MnO4--Compounds with low oxidation states are often reducing
agents e.g V2+ & Fe2+
◉ four colour and symbol stages of Vanadium. Answer: VO2+
Oxidation state +5 ( a yellow solution)
VO2+ Oxidation state + 4 (a blue solution)
, V3+ Oxidation state + 3 (a green solution)
V2+ Oxidation state + 2 (a violet solution)
YOU BETTER GET VANADIUM
◉ what is used to reduce vanadium. Answer: Addition of zinc to the
vanadium (V) in acidic solution will reduce the vanadium down
through each successive oxidation state, and the colour would
successively change from yellow to blue to green to violet
◉ what is used in testing for aldehydes. Answer: [Ag(NH3)2]+ is used
in Tollen's reagent to distinguish between aldehydes and ketones .
Aldehydes reduce the silver in the Tollen's reagent to silver
◉ why are dark colours of solutions difficult to measure. Answer:
The purple colour of manganate can make it difficult to see the
bottom of meniscus in the burette.
◉ what acid is used for manganate titrations. Answer: Only use
dilute sulphuric acid for manganate titrations.
Insufficient volumes of sulphuric acid will mean the solution is not
acidic enough and MnO2 will be produced instead of Mn2+.
Using a weak acid like ethanoic acid would have the same effect as it
cannot supply the large amount of hydrogen ions needed (8H+).
It cannot be conc HCl as the Cl- ions would be oxidised to Cl2
PAPER 2026 QUESTIONS WITH
SOLUTIONS GRADED A+
◉ 4 main characteristics of Transition metals. Answer: complex
formation, formation of coloured ions, variable oxidation state,
catalytic activity
◉ what is a complex. Answer: a central metal ion surrounded by
ligands
◉ what is a ligand. Answer: An atom, ion or molecule which can
donate a lone electron pair
◉ what is a coordinate bond. Answer: Co-ordinate bonding is when
the shared pair of electrons in the covalent bond come from only one
of the bonding atoms
◉ what is coordination number. Answer: The number of co-ordinate
bonds formed to a central metal ion
◉ why is carbon monoxide toxic. Answer: CO is toxic to humans as
CO can from a strong coordinate bond with haemoglobin. This is a
,stronger bond than that made with oxygen and so it replaces the
oxygen attaching to the haemoglobin
◉ what is the chelate effect. Answer: The substitution of
monodentate ligand with a bidentate or a multidentate ligand leads
to a more stable complex. This chelate effect can be explained in
terms of a positive entropy change in these reactions as more
molecules of products than reactants
◉ type of isomerism shown in square planar/octahedral complexes.
Answer: E-Z
◉ isomerism shown only in octahedral complexes. Answer:
Complexes with 3 bidentate ligands can form two optical isomers
(non-superimposable mirror images)
◉ how do transition metals show colour. Answer: Colour arises from
electronic transitions from the ground state to excited states:
between different d orbitals.
A portion of visible light is absorbed to promote d electrons to higher
energy levels. The light that is not absorbed is transmitted to give the
substance colour.
◉ what is the equation which links the colour and frequency of the
light absorbed with the energy difference between the split d
orbitals. Answer: E = hv.
,v = frequency of light absorbed (unit s-1 or Hz) h= Planck's constant
6.63 × 10-34 (J s)
E = energy difference between split orbitals (J)
◉ how can you change colour of transition metals. Answer:
Changing a ligand or changing the coordination number will alter the
energy split between the d- orbitals, changing E and hence change
the frequency of light absorbed
◉ describe the method of spectroscopy. Answer: •Add an
appropriate ligand to intensify colour •Make up solutions of known
concentration (dilution series)
•Measure absorption or transmission
•Plot graph of absorption vs concentration •Measure absorption of
unknown and compare
◉ general trend of variable oxidation states. Answer: - Relative
stability of +2 state with respect to +3 state increases across the
period
- Compounds with high oxidation states tend to be oxidising agents
e.g MnO4--Compounds with low oxidation states are often reducing
agents e.g V2+ & Fe2+
◉ four colour and symbol stages of Vanadium. Answer: VO2+
Oxidation state +5 ( a yellow solution)
VO2+ Oxidation state + 4 (a blue solution)
, V3+ Oxidation state + 3 (a green solution)
V2+ Oxidation state + 2 (a violet solution)
YOU BETTER GET VANADIUM
◉ what is used to reduce vanadium. Answer: Addition of zinc to the
vanadium (V) in acidic solution will reduce the vanadium down
through each successive oxidation state, and the colour would
successively change from yellow to blue to green to violet
◉ what is used in testing for aldehydes. Answer: [Ag(NH3)2]+ is used
in Tollen's reagent to distinguish between aldehydes and ketones .
Aldehydes reduce the silver in the Tollen's reagent to silver
◉ why are dark colours of solutions difficult to measure. Answer:
The purple colour of manganate can make it difficult to see the
bottom of meniscus in the burette.
◉ what acid is used for manganate titrations. Answer: Only use
dilute sulphuric acid for manganate titrations.
Insufficient volumes of sulphuric acid will mean the solution is not
acidic enough and MnO2 will be produced instead of Mn2+.
Using a weak acid like ethanoic acid would have the same effect as it
cannot supply the large amount of hydrogen ions needed (8H+).
It cannot be conc HCl as the Cl- ions would be oxidised to Cl2
