Oxford Cambridge and RSA - 2025
Friday 20 June 2025 – Morning
A Level Chemistry B (Salters)
H433/03 Practical skills in chemistry
Time allowed: 1 hour 30 minutes
(Verified Question Paper With Mark
Scheme Combined June 2025)
, INSTRUCTIONS
• Use black ink. You can use an HB pencil, but only for graphs and diagrams.
• Write your answer to each question in the space provided. If you need extra
space use the lined page at the end of this booklet. The question numbers
must be clearly shown.
• Answer all the questions.
• Where appropriate, your answer should be supported with working.
Marks might be given for using a correct method, even if your answer is
wrong.
INFORMATION
• The total mark for this paper is 60.
• The marks for each question are shown in brackets [ ].
• Quality of extended response will be assessed in questions marked with an
asterisk (*).
• This document has 16 pages.
ADVICE
• Read each question carefully before you start your answer.
© OCR 2025
OCR is an exempt
[601/5371/4] DC
Charity Turn over
(PQ/CT) 344775/3
, 2
1 This question is about the properties of some Group 2 alkaline earth metals and their
compounds.
(a)
(i) The term ‘alkaline’ refers to oxides and hydroxides of the Group 2 elements.
Explain why calcium oxide is described as
alkaline. Include an appropriate equation.
Explanation: ......................................................................................................................
...............
............................................................................................................................................
..............
Equation:
[2]
(ii) Explain why the Group 2 elements are known as s block elements.
............................................................................................................................................
..............
.................................................................................................................................. [1]
(b) Strontium sulfate is used in fireworks. Strontium gives a red colour when ignited.
A frequency of red light from the strontium spectrum is 4.62
× 1014 Hz. Calculate the energy per mole of photons of this
frequency in kJ mol–1. Give your answer to an appropriate
number of significant figures.
Energy = ........................................... kJ mol–
1
[3]
© OCR
2025
, 3
(c) Barium sulfate is very insoluble in water.
(i) Solutions containing sulfate ions give a white precipitate with barium chloride solution.
Write an ionic equation for the formation of this white
precipitate. Include state symbols.
[1]
(ii) A solution has [SO
4
2–
] = 0.10 mol dm–3.
Calculate the smallest [Ba2+] in the solution which will just give a white
precipitate. For barium sulfate, Ksp = 1.0 × 10–10 mol2 dm–6.
[Ba2+] = .......................................... mol
dm–3 [2]
(d) Calcium and potassium are in the same period of the periodic table.
Explain why calcium has the higher melting point.
............................................................................................................................................
..............
............................................................................................................................................
..............
............................................................................................................................................
..............
.................................................................................................................................. [2]
© OCR Turn over
2025
Friday 20 June 2025 – Morning
A Level Chemistry B (Salters)
H433/03 Practical skills in chemistry
Time allowed: 1 hour 30 minutes
(Verified Question Paper With Mark
Scheme Combined June 2025)
, INSTRUCTIONS
• Use black ink. You can use an HB pencil, but only for graphs and diagrams.
• Write your answer to each question in the space provided. If you need extra
space use the lined page at the end of this booklet. The question numbers
must be clearly shown.
• Answer all the questions.
• Where appropriate, your answer should be supported with working.
Marks might be given for using a correct method, even if your answer is
wrong.
INFORMATION
• The total mark for this paper is 60.
• The marks for each question are shown in brackets [ ].
• Quality of extended response will be assessed in questions marked with an
asterisk (*).
• This document has 16 pages.
ADVICE
• Read each question carefully before you start your answer.
© OCR 2025
OCR is an exempt
[601/5371/4] DC
Charity Turn over
(PQ/CT) 344775/3
, 2
1 This question is about the properties of some Group 2 alkaline earth metals and their
compounds.
(a)
(i) The term ‘alkaline’ refers to oxides and hydroxides of the Group 2 elements.
Explain why calcium oxide is described as
alkaline. Include an appropriate equation.
Explanation: ......................................................................................................................
...............
............................................................................................................................................
..............
Equation:
[2]
(ii) Explain why the Group 2 elements are known as s block elements.
............................................................................................................................................
..............
.................................................................................................................................. [1]
(b) Strontium sulfate is used in fireworks. Strontium gives a red colour when ignited.
A frequency of red light from the strontium spectrum is 4.62
× 1014 Hz. Calculate the energy per mole of photons of this
frequency in kJ mol–1. Give your answer to an appropriate
number of significant figures.
Energy = ........................................... kJ mol–
1
[3]
© OCR
2025
, 3
(c) Barium sulfate is very insoluble in water.
(i) Solutions containing sulfate ions give a white precipitate with barium chloride solution.
Write an ionic equation for the formation of this white
precipitate. Include state symbols.
[1]
(ii) A solution has [SO
4
2–
] = 0.10 mol dm–3.
Calculate the smallest [Ba2+] in the solution which will just give a white
precipitate. For barium sulfate, Ksp = 1.0 × 10–10 mol2 dm–6.
[Ba2+] = .......................................... mol
dm–3 [2]
(d) Calcium and potassium are in the same period of the periodic table.
Explain why calcium has the higher melting point.
............................................................................................................................................
..............
............................................................................................................................................
..............
............................................................................................................................................
..............
.................................................................................................................................. [2]
© OCR Turn over
2025
