Killed by multiple choice? (1 Viewer)

Drewx

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pH adjustment -> Flocculation -> Settling

It's b) no two buts about it
 

shaon0

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pH adjustment is one of the last steps.
Yeah, pH adjustment is almost the last step. In relation to the topic; 13-15/15 depending on the answers to the last 2 MC.
 
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kenshinx77

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OK OK OK
i think the answers of MC from cross- referencing are

1.C
2.C
3.D
4.C
5.A
6.D (got this wrong xD)
7.B
8.A
9.A (again got this wrong -_-')
10.B
11.D
12.A
13.B
14.A (i did the calculation and it worked out to be 1.0385)
15.C (i think?)
 

kieranjackson91

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I'm reading the Excel book NOW. It says PH adjustment is basically last.



It says Flocc>Sedi>PH

Guess I'm right, 11D.
you shouldnt guess you're right lol. btw I used conquering chemistry 4th edition, and it clearly says pH is adjusted before flocculation (it doesn't say anything about pH adjustment afterwards). This is interesting that textbooks say different things, how nasty of the board of studies.
 

shaon0

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you shouldnt guess you're right lol. btw I used conquering chemistry 4th edition, and it clearly says pH is adjusted before flocculation (it doesn't say anything about pH adjustment afterwards). This is interesting that textbooks say different things, how nasty of the board of studies.
I've been told before that it is flocculation->sedimentation->pH adjustment by reliable sources.
 

GT03

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From memory Macqurie said pH adjustment is done AFTER.
But i see where people are coming from about adding lime --> raises pH.
I put pH adjustment afterwards ...by the look of it i think i've gotten it wrong.pH adjustment before chlorination is a bit odd.
Either way I'd say its an ambiguous questions.. damn BOS
I reckon i got 13/15..got that one and 14 wrong :(
 

Thecorey0

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Seems to be a pretty dodgy question. Each textbook seems to say differerent things. In a situation like this, reckon the markers would ever except two answers?
 

4theHSC

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Seems to be a pretty dodgy question. Each textbook seems to say differerent things. In a situation like this, reckon the markers would ever except two answers?
They will probably take into account both answers
 

kieranjackson91

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I've been told before that it is flocculation->sedimentation->pH adjustment by reliable sources.
perhaps the question was asking about the clarification of water, and in what order that was done. I didn't keep the exam but I think option B in the question was something like [pH adjustment]> [flocculation]> [settling]?

correct me if i'm wrong

yes i think it was an ambiguous question, note how in HSC Online it actually says: 'There are several methods used to purify mass water supplies. Most are variations on the following process: bla bla..'
 

blabla91

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Yes pH adjustment occurs AFTER, AT THE END, ONE OF THE LATER PROCESSES BLA BLA BLA BUTTTT this is AFTER chlorination in effect it looks like this

pH adjustment --> flocculation --> sedimentation --> chlorination --> pH adjustment
 

boxhunter91

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I got it in my book.
These are the processes to sanitise water in order:
Screening
Aeration
Flocculation
Sedimentation
Filtration
Chlorination
pH adjustment
Fluoridation
 

Blaz-357

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Fuck, i swear the MC this year was hard than previous...i no ive definitely got 3 wrong atm, the bloody Barium flame colourtest...i crossed out green immediately LOL thought copper made green...-.-", and the shitty critic acid! i fuking forgot to divide the moles by 3! OMG FUKING FAIL T_T and fuking the last q, 15...lol i thought i was c at first but i was panicing had like 2 minutes to do it...(left it till last) but den i was like g/mol cant be V...so i wrote A...omg mega fail...FML
 

sordatsoy

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what is the answer to that chromium question...sorry i dont have the paper so i cant check with the answers you've given. I got B
 

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