Mark Scheme (Results)
Summer 2023
Pearson Edexcel International GCSE
In Physics (4PH1) Paper 1P
, Question
Answer Notes Marks
number
1 (a) A (becquerel); 1
B is incorrect because it is the unit of mass
C is incorrect because it is the unit of force
D is incorrect because it is the unit of pressure
(b) A (time taken for the activity of a substance to 1
halve);
B is incorrect because the substance will not
completely decay
C is incorrect because the substance will not
completely decay
D is incorrect because the substance cannot decay
twice
(c) (i) stopwatch; 2
GM tube;
(ii) point at t = 20s identified; 1
(iii) any indication of a halving in activity; e.g. 50→25 2
40→20 etc. seen in
working
allow ÷2, ×½ seen in
working
half-life = 15 (s); allow full credit in
range 14−16 (s)
(iv) any indication that decay is random; allow unpredictable 1
allow references to
background
radiation/count varying
Total for Question 1 = 8 marks
Summer 2023
Pearson Edexcel International GCSE
In Physics (4PH1) Paper 1P
, Question
Answer Notes Marks
number
1 (a) A (becquerel); 1
B is incorrect because it is the unit of mass
C is incorrect because it is the unit of force
D is incorrect because it is the unit of pressure
(b) A (time taken for the activity of a substance to 1
halve);
B is incorrect because the substance will not
completely decay
C is incorrect because the substance will not
completely decay
D is incorrect because the substance cannot decay
twice
(c) (i) stopwatch; 2
GM tube;
(ii) point at t = 20s identified; 1
(iii) any indication of a halving in activity; e.g. 50→25 2
40→20 etc. seen in
working
allow ÷2, ×½ seen in
working
half-life = 15 (s); allow full credit in
range 14−16 (s)
(iv) any indication that decay is random; allow unpredictable 1
allow references to
background
radiation/count varying
Total for Question 1 = 8 marks
