multiple choice...WTF? (1 Viewer)

[SmileyCam]

dude, ur h2so4 is stuffed, its a strong acid

yes, but it still establishes an equilibrium reaction that does not FULLY ionise, so it's not exactly 1, and it's an acid so it's more then 7

 

[~ ReNcH ~]

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

 

[richz]

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

Rench u dont need phys for q 5, think about it, can u acutally see electrons move??

 

[queenie]

yes, but it still establishes an equilibrium reaction that does not FULLY ionise, so it's not exactly 1, and it's an acid so it's more then 7

thats industrial stuff, is it not?

 

[richz]

yes, but it still establishes an equilibrium reaction that does not FULLY ionise, so it's not exactly 1, and it's an acid so it's more then 7

um.. h2so4 is diprotic...

 

[queenie]

um.. h2so4 is diprotic...

yea it is, but what industrial kids are taught:

h2so4 --> H+ + Hso4-

then
Hso4 = (eqm) H+ + so42-

but... the point is, that thats taught in the elective.

generally, h2so4 is diprotic, so the answer would have been a.

 

[~ ReNcH ~]

Rench u dont need phys for q 5, think about it, can u acutally see electrons move??

Yea, I know. I realised that afterwards too
But I considered that maybe a reading on the voltmeter would indicate a movement of electrons...ah well, I regret not putting B coz I was making a 50/50 toss-up but it's too late now I guess.

 

[physician]

I agree that B and D could both be correct... I have my doubts though and im beginning to think it is B, but neways I put D..B seemed correct at the time, but then something clicked and I ended up puting D...meh!

(1) D
(2) C
(3) B
(4) D (lucky guess prolly.. according to what u guy answered)
(5) B
(6) A
(7) A (yes!, i agree it's wrong)
(8) C (..bah just realised i made a silly mistake, its less than 1, i thought i got 6.9 on my calculator..instead of 0.69... )
(9) B (just a guess...seeing as it was different to all the others)
(10) C (pritty staright forward)
(11) A
(12) B
(13) C
(14) D... the water at the river source will have a PH very close to 7 (7 being neutral)... therefore its not B or C, and site 3 is most basic therefore its D.... My reasoning..lol)
(15) C, a guess from Mars!!!...(the question required too much concentration/reading and i literally only got 2 hours sleep before the exam so i couldnt be stuffed)

I think that should get me about 11/15.......Arg, could've done so muc better!..oh well!

 

[~ ReNcH ~]

yea it is, but what industrial kids are taught:

h2so4 --> H+ + Hso4-

then
Hso4 = (eqm) H+ + so42-

but... the point is, that thats taught in the elective.

generally, h2so4 is diprotic, so the answer would have been a.

According to a Google search, acetic acid/acetate can be used as a buffer, so I think the answer is D.

 

[rama_v]

According to a Google search, acetic acid/acetate can be used as a buffer, so I think the answer is D.

Yayyy I put that as a guess

 

[~ ReNcH ~]

I'm still just unsure about Q1.
If B) were "Too many protons or neutrons in the atom", then it would definitiely be B but the "and" changes things a lot.

 

[physician]

I'm still just unsure about Q1.
If B) were "Too many protons or neutrons in the atom", then it would definitiely be B but the "and" changes things a lot.

exacty! but as ppl have suggested, it wasnt in terms of the ratio, merely the fact that radiocative is for atomic number > 83

but if thats the case, then the answer is misleading, because how much is TOO many?

and the ratio is neutrons/protons, but it doesnt matter, because whether its 1.6/1 or 1/1.6, the ratio is still indicative that the ratio is not the ideal ratio for a stable isotope!

meh.. this is confusing

well its not ( A ), neither is it ( C ).. agreed?

meh, who knows...!

 

[richz]

Yea, I know. I realised that afterwards too
But I considered that maybe a reading on the voltmeter would indicate a movement of electrons...ah well, I regret not putting B coz I was making a 50/50 toss-up but it's too late now I guess.

lol, i had d too, i was thinking about it, then i realised, how da hell are u ment to see electrons move, luckily i changed it . And yeah 9 is D, as one person posted, a buffer is a weak acid + conjugate base. argh i misread the question again, i related the q to an amphiprotic substances, argh...

 

[laserbrainz]

According to a Google search, acetic acid/acetate can be used as a buffer, so I think the answer is D.

that's the answer (weak acid/salt of that acid)

as for 15, thiosulphate/o2 ratio is 4: 1, but if you go through the equations, that halves again, = 0.30

i got 0.052% for the calc % whatever it was with the TDS one as well (yay, i can do some chem) - not my strongest subject.

As for me, q4 took ages - came back, & it was ok the second time - got d as well.

 

[Captain Gh3y]

Acetate ions was the only base that wasn't extremely weak (Cl-), not a base at all, or not the conjugate of the acid.

Only B can be correct in the nuclear q'n, for reasons I don't care to explain again, read my post on page 3.

Electrons moving is an inference not an observation.

 

[holla back girl]

According to a Google search, acetic acid/acetate can be used as a buffer, so I think the answer is D.

a buffer consists of comparable amounts of a weak acid with its conjugate base (one less proton than the acid)

it has to be acetic acid!

 

[holla back girl]

my answers...
b
c
b
d
b
a
c
a
d
c
a
b
c
d
b

i have a feeling that they are all right...
although theres some debate on 15

 

[richz]

thnx captian obvious, thats what he just said

 

[~ ReNcH ~]

that's the answer (weak acid/salt of that acid)

as for 15, thiosulphate/o2 ratio is 4: 1, but if you go through the equations, that halves again, = 0.30

i got 0.052% for the calc % whatever it was with the TDS one as well (yay, i can do some chem) - not my strongest subject.

As for me, q4 took ages - came back, & it was ok the second time - got d as well.

Q15: I'm fairly sure it's A.
n(I₂) = 0.5n(S₂O₃)
n(I₂) = n(MnO(OH)₂)

n(O₂) = 0.5n(MnO(OH)₂) = 0.5n(I₂) since n(MnO(OH)₂ = n(I₂)
but n(I₂) = 0.5n(S₂O₃)

.'. n(O₂) = 0.5 x 0.5 x n(S₂O₃) = 0.15

Then again, who knows if my reasoning is right.

 

[>monkey<]

i think i got about 10 or 11 outta 15 from the multiple choice which im not very happy with!
i think question 1 is D, because if there are to many electrons to neutrons then there are also to many protons to neutrons becuase no. electrons = no. protons! that wuld mean that the N ratio is to small and the atom is unstable!
wat did u guys think?