[Fish200398]

1 g each of these dissolve in 1 L water
1. Glucose
2. Sodium chloride
3. Sodium sulfate
4. Magnesium chloride

My answer :
Glucose is the lowest, due to covalent bonding with no hydrogen forces not ionic

Na2so4 Nacl and mgcl2
But what about these 3?
Should i count it wih formula of t=i*kb*b
b = molality
Kb = constanta
i = van hoff factor

[mjc123]

Should i count it wih formula of t=i*kb*b

Yes. Same for glucose - ionic vs. covalent is irrelevant - and it does have hydrogen bonding.

[AWK]

according to your formula t/kb=i*b should show the highest value. Compare all i*b values.

[Fish200398]

After i calculated, i get nacl = 0.035, and mgcl2 = 0.0315, so highest is nacl
But the answer isnt nacl, why?

[AWK]

From the question:
"Order the one has the highest boiling point to lowest"
I understand that the answer should be:
eg.) 1>3>2>4 or 1,3,2,4

[Fish200398]

Tell me how to conclude that?

[AWK]

Order - the highest boiling point  - to lowest

[Fish200398]

Tell me how do i decide which one is higher and lower?

[mjc123]

You were on the right lines before. @AWK is simply pointing out that the question doesn't say "which is highest?" but "put them in order".

[Fish200398]

Ok. But the highest isnt nacl, why is it wrong then?

[Fish200398]

From my calculation nacl is bigger than mgcl2, but why the answer mgcl2 has higher boil point than nacl?

[Borek]

Must be an error, I got the same numbers as you did for NaCl and MgCl₂ and your conclusion that NaCl has the highest boiling point looks OK.

Technically i for MgCl₂ will be lower than 3 due to the ion association, whether you should account for that or nor depends on the course level. If that is a HS course i=3 is a reasonable first approximation.

[Fish200398]

Really? Thanks borek and all

[AWK]

Four months ago there was an analogous question (using 10 g of substances)  with the same wrong answer: magnesium chloride
https://chemistry.stackexchange.com/questions/118229/which-one-has-the-highest-boiling-point

Please, give the source of your problem

[Fish200398]

Yes. I found it but i already posted here. What do i do by "give source of problem"