multiple choice...WTF? (3 Viewers)

[ART]

cool discovery

hey peeps! yeh, i think the multiple choice was pretty okay. It was the larger mark questions that stressed me out:
the esterification/ fermentation question: "omg!! have i missed something out? stress stress"
anywayz, im studying for modern (its gonna be a long nite) and have made a discovery: brushing your teeth keeps u awake! so i am off to study while brushin teeth! super clean!!!!!!!
ciao

 

[lum]

guys, now that i think about it, 11 should be B. i put A myself, but rereading the damn question, it asked which was best analysed by aas, now i dunno bout you, but for calcium, hell adding F- or H2S04 or even the bloody brick red flame test is easier than using AAS, while iodine can ONLY be analysed by AAS (known to us).

what do you think?

 

[Ultraviolent]

guys, now that i think about it, 11 should be B. i put A myself, but rereading the damn question, it asked which was best analysed by aas, now i dunno bout you, but for calcium, hell adding F- or H2S04 or even the bloody brick red flame test is easier than using AAS, while iodine can ONLY be analysed by AAS (known to us).

what do you think?

This is scary...

edit: definitely ambiguous, though...

 

[Captain Gh3y]

guys, now that i think about it, 11 should be B. i put A myself, but rereading the damn question, it asked which was best analysed by aas, now i dunno bout you, but for calcium, hell adding F- or H2S04 or even the bloody brick red flame test is easier than using AAS, while iodine can ONLY be analysed by AAS (known to us).

what do you think?

Starch.
Starch.
Starch.

AAS = Metals.

Iodine ions are I^-. In the syllabus it talks about AAS to test for cations.

 

[gogogadgetbrain]

yes AAS is used to detect metallic ions but it can also be used to detect other non-metals
dont get me wrong i put A too BUT the way the question was worded was dodgey

as calcium is better detected by other methods and iodine is best detected by AAS
however AAS is better at detecting calcium than iodine....thats where my textbooks have me confused

but like i said before, its all over red rover and there's shit all we can do about it..hahha unless you want to protest one minor question in what was a painfully simple test

 

[Captain Gh3y]

You may be right. But you're bringing real chemistry into this. Remember, this HSC Chemistry, where the syllabus is king.

 

[khalidm]

It was definitely the hardest multiple-choice session I have done. I got Q1 wrong (wrote D (electrons : neutrons) instead of B (protons : neutrons)).

And 15 was A (0.15).

YAAAAAAAY that means i got it right tooooooo!!!
come on ppl, multiple choice wasn't THAT bad, i reckon the test was pretty good. the battery question stuffed me around though, had to fudge the answer (on the advice of my chem teacher, "if you dont know the answer....fudge it."
peace out ppl and best for all

 

[ifsonotso_100]

i didn't bother to read everything but the only answer for the radioactive one is b, why because transuranic elements are greater than 83 so when it says protons and neutrons if there are tonnes unstable, also the electron to neutron ratio is completely wrong, if it was the other way it may have been feasible, looks like i got 14/15 for the mc, looks like i got the last one wrong, but that is an awesome mark for me

 

[gogogadgetbrain]

You may be right. But you're bringing real chemistry into this. Remember, this HSC Chemistry, where the syllabus is king.

hahaha.. you're so right,- god knows what would happen if students could extend their chemistry knowledge beyond the syllabus! what would be next... turning the sciences into humanities?

 

[jcl]

It is definitely Calcium. Here's why:

1. You can't have both 11 and 12 as B. It would interrupt the zig-zag pattern.
2. If it was B, you'd have 5 B's, 4 C's 3 A's and 3 D's (alphabetical prejudice in the NSW syllabus? I think not) rather than the more logical 4 A B and C and 3 D...

duh

 

[Moonlite]

I got 11/15... i'm quite happy, since the ones I guessed turned out right.

 

[JumboKHS]

Can someone please explain to me question 12 with the experiment repetition. Everyone seems to be going for reliability but i put accuracy for acouple of reasons. Reason 1, our junior science teacher burnt into our head that for every experimental procedure we write these exact words as our final step to the procedure "repeat step to improve accuracy", and she was a HSC examiner. Reason 2, The main reason that you repeat an experiment is so that you can take an average of your answers and then your final answer becomes more of an answer that other people would expect to get because it is an average answer. For example say so do an experiment and you get the answers 7,8 and 9 and the values 7 and 9 were the complete extremes of the experimental results that you could have gotten. So you take an average and put 8 and thus the maximum error you can get is being off by 1 unit., but if u didnt repeat to take an average and you put down 7 your error range would have been 2, thus because your answer has a smaller error range from repetition doesnt that mean your answer is more accurate??

My reasoning against choosing reliability was because i beleived that the reliability of an experiment sort of went hand in hand with the validity of an experiment, which i beleive is based on the actual procedure you do, not the repetition process. For example someone may do an experiment to calculate the molar heat of ethanol but doesnt actually use pure ethanol or does something quite unorthadox and thus the results become unreliable because the procedure differs to textbook procedures? However even if his experiment for his molar heat calculation may have used the wrong procedure and returned unreliable results, by repeating the experiment his final answer becomes more accurate for the actual experiment he did end up doing.


So can someone please shed some light on this

 

[justchillin]

reliability: are we able to reproduce the results; the consistancy of the results
accuracy: percision of equipment and measurments
validility: is the method appropriate for testing the particular characteristical feature thats's being tested.
Hence repeating exp will increase reliability as it demonstrates consistancy in the results.
The AAS is calcium because it is metallic ions that absord the known wavelengths(due to the way the electrons move in their shells)...
Question one is B...though technically if they said atom then D is also correct, defonition of atom: neutral - ie same number of neutrons and protons.
14 D - I had a brain freeze and thought that a ph above 7 was acidic (I always do that)
And 15 was A no doubt - just follow the mole ratios and it comes out.
13/15 multi... 94/95 exam...

 

[Oso]

I think the problem everyone was having with 15 was that they included the Oxygen from the 4OH molecules in the original.
I took it to mean only O2 so I said A.

 

[Kyroth***]

I just realised such a stuff up! I was looking at everyone's answers, and you all have 2C! And I'm thinking "It can't be 2C, its 2A!" Because all polymers are carbon based, and all organic things are carbon based, so that doesn't make cellulose special at all. What makes cellulose special is that it is easily available all over the world, hence A. So I re-read the question, thinking som,ething was amiss, and then I saw, the question is what makes is a fuel source, not what makes it an ALTERNATIVE fuel source!!! *crys* Multiple choice are my best ones, and now I've screwed them up!!!

 

[seadonkey]

Q1 I said B, but I also considered D to be correct...who knows?
Q5 I got wrong...I said D, and having not done physics was later told that electrons don't flow through a voltmeter so meh.
Q14 I said D
Q15 I said A - I'm fairly sure of this one.

So depending on Q1, I'm hoping for 13-14/15:

B
C
B
D
D (wrong)
A
C
A
D
C
A
B
C
D
A

if u do phy ud know 1 isnt D, its B
n they only reason y 5 is B is cos electrons moving is a deduction, not something u c [electrons do move thru voltmeter - thats is a result of applied voltage]

 

[seadonkey]

I just realised such a stuff up! I was looking at everyone's answers, and you all have 2C! And I'm thinking "It can't be 2C, its 2A!" Because all polymers are carbon based, and all organic things are carbon based, so that doesn't make cellulose special at all. What makes cellulose special is that it is easily available all over the world, hence A. So I re-read the question, thinking som,ething was amiss, and then I saw, the question is what makes is a fuel source, not what makes it an ALTERNATIVE fuel source!!! *crys* Multiple choice are my best ones, and now I've screwed them up!!!

i put 2C
quote from the syllabus: "cellulose contains the basic carbon structure that can be converted to petrochemicals"

as well as option C says ORGANIC polymer

 

[alia]

reliability and diprotic

Because H2SO4 is diprotic then there is double the [H+] concentration. So it is -log0.2 which is around 0.69, but because the second ionisation thing is weaker, it is tachnically around 0.9, so it is still less than one. so A

Reliability is improved by repeating experiments and getting the same results

 

[punki_pixi]

About the accuracy vs reliability thing, in the Success One Chemistry book one of the questions said how would you improve the accuracy of the experiment and the answer was to use repetition. These people write papers and mark them so why would they say that if the answer to the multiple choice question in our exam wasn't accuracy?

 

[spongeab]

hey i have a query. for Q1 in multiple choice (d) it said "too many electrons for the number of neutrons in the atom".. aint the number of electrons equal to the number of protons.. so therefore its saying that the proton to neutron ratio is too high and thats wat would produce a radioactive isotope?? well that was my reasoning anyway so dammit if its wrong lol.