Naming CFC (2 Viewers)

[wolsty7]

why is the answer "c", shouldn't it be "a"?

 

[madharris]

I think it's because you give lowest numbers to most electronegative halogen: F>Cl>Br>I

 

[Menomaths]

I think it's because you give lowest numbers to most electronegative halogen: F>Cl>Br>I

That rule applies after all the other rules don't work(i.e more than 1 answer). In this case Cl comes first alphabetically... I would have gone for OP's answer but I don't know anymore...

 

[AB940]

I was always taught that it was alphabetical order with the halogens. I would've answered A but now I'm also confused.
Organic nomenclature was my least favourite part of chemistry.

 

[madharris]

That rule applies after all the other rules don't work(i.e more than 1 answer). In this case Cl comes first alphabetically... I would have gone for OP's answer but I don't know anymore...

Oh my bad Forgotten my chemistry :\

 

[AnimeX]

Yup it's alphabetical, OP you're right.

Which book is this btw?

 

[Menomaths]

Looks like a past paper

 

[wolsty7]

a catholic school past trial paper, not sure which one tho

 

[jaycoo50]

View attachment 28596

why is the answer "c", shouldn't it be "a"?

No One could answer this easy question and your also wrong! Learn to study smart, you had to memorise the rules of naming them! It took me 1 second to work out the answer

lol the answer is c, because the chlorine is on the 5 carbon while the fluorine is on the 3 carbon. so alphabetical chloro comes first followed by fluoro, so the answer is:
c) 5-chloro-3-fluoroheptane. Note that: Heptane means 7 carboon, don't confuse your self in HSC!

you are confusing option A with C, option A is right, but alphabetical the numbers are opposite. In Option A you can see, that Chlorine is not on the 3 carbon. Hence option is a is wrong.

 

[AnimeX]

No One could answer this easy question and your also wrong! Learn to study smart, you had to memorise the rules of naming them! It took me 1 second to work out the answer

lol the answer is c, because the chlorine is on the 5 carbon while the fluorine is on the 3 carbon. so alphabetical chloro comes first followed by fluoro, so the answer is:
c) 5-chloro-3-fluoroheptane. Note that: Heptane means 7 carboon, don't confuse your self in HSC!

you are confusing option A with C, option A is right, but alphabetical the numbers are opposite. In Option A you can see, that Chlorine is not on the 3 carbon. Hence option is a is wrong.

"Assemble the components into a complete name, with the halogen and side group
names placed in front of the main stem name, in alphabetical order, ignoring any di-,
tri-, tetra-, etc prefixes. Eg 'dibromo' comes before 'chloro'," ...." the lowest locant is assigned to the functional group cited first
as a prefix." pg 4: http://www.raci.org.au/document/item/1012

 

[AB940]

No One could answer this easy question and your also wrong! Learn to study smart, you had to memorise the rules of naming them! It took me 1 second to work out the answer

lol the answer is c, because the chlorine is on the 5 carbon while the fluorine is on the 3 carbon. so alphabetical chloro comes first followed by fluoro, so the answer is:
c) 5-chloro-3-fluoroheptane. Note that: Heptane means 7 carboon, don't confuse your self in HSC!

you are confusing option A with C, option A is right, but alphabetical the numbers are opposite. In Option A you can see, that Chlorine is not on the 3 carbon. Hence option is a is wrong.

It's not left-to-right with nomenclature, that's just the way they're often drawn as a convenience. If you swapped the to halogen groups around on this particular molecule and just flipped it around you'd get the exact same one, so it is the same molecule. (this wouldn't apply if the two halogens weren't equidistant to the end of the carbon chain).

 

[Riproot]

I think it's because you give lowest numbers to most electronegative halogen: F>Cl>Br>I

I was taught this way
And never got any of these questions wrong
So I'd go with this

 

[anomalousdecay]

I was taught this way
And never got any of these questions wrong
So I'd go with this

No. OP is correct. Look at the 2012 HSC. Look at question 12 and the answer given by board of studies.
There is a little annotation explaining the answer as D.