I WOULD like to draw the attention of the Examination Syndicate to the SPM Physics papers.
Question No 12 (Paper 1, 2009) is definitely out of the present syllabus. The question is: Butane gas leakage happens in a laboratory preparation room. A teacher in the adjacent laboratory smells the odour even though no wind is blowing. The phenomenon happens because of: A condensation, B diffusion, C evaporation, D expansion.
The expected answer I suppose is B diffusion. Before I discuss the answer, I would first like to point out that this question IS NOT in the SPM Physics syllabus.
Incidentally, Question 11 (Paper 1, 2008) on Brownian Motion is also not in the syllabus.
Both diffusion and Brownian Motion were in the syllabus before 2006 under the section of properties of matter (Chapter 3, Form 4 ). But this section had been taken out from the syllabus.
Should topics not mentioned in the current syllabus be tested? The Physics panel may argue that these topics are in the Form 1 syllabus, or that diffusion is in Chemistry syllabus! Then what is the syllabus for?
Perhaps the panel does not know the syllabus well. They might have just chosen the questions from the Question Bank without reviewing the syllabus. The Question Bank may still have some questions from the previous syllabus.
Did the syndicate take the trouble to throw out those questions which are no longer in the syllabus?
Now back to Q12 2009.
Is the supposed answer diffusion the correct one? In his book: Physics (Fifth edition, Prentice Hall), pg 410, Giancoli shows that air currents (convection) are more important than diffusion in transmitting odours. Giancoli shows that it takes about two minutes for ammonia (NH 3) to be detected 10cm away from a bottle containing ammonia after it is opened. The diffusion rate of butane (C4H10 ) is even slower.
Diffusion, which is rather slow, alone would not have enabled the teacher to smell the odour.
Cutnell and Johnson also use the same reasoning in Physics (Fourth Edition, Wiley).
So now when Mrs Smith is preparing a cup of coffee, you smell the aroma right away in the question hall. Is this due to convection or diffusion alone?