It's the 2006 particle physics question 10.(a) One part of the question says "Pions are mesons that consist of up and down quarks and their antiquarks. Give the quark composition of (i) a positive pion and (ii) a negative pion." The question is worth 9 marks. In the marking scheme part (i) is worth 3 marks and (ii) is worth 3 marks. They also have in the marking scheme 3 marks for writing "any quark, antiquark pair" what does this mean and why would you think to write this if it's not specifically asked in the question? Thanks.