Thanks guys
I got 38/40, t'was really awesome cause i got 26 on my mock
I'll be posting more 2009 papers. I already got the Portuguese and English First Language. There are no Mark Schemes for them. I'm still going to get the Economics, Physics and Biology Paper 1 and I'll try to get the mark scheme if my teachers have availability.
And By the way, it is in fact calcium (A) because it is the only metal and when it reacts with oxygen, it forms an alkali (or basic oxide) (calcium oxide). So, it was the only one which can turn litmus paper blue.
To the helium one, i don't think the question was quite relating to the filament but in fact, to your knowledge about the composition of air and the trends in the noble gases (the further down you go on the group, the more dense they are)