HELP HELP!

[Lost_Life]

Just one tiny wincy question..WHY IS THE ANSWER A TO JANUARY 2010 QUESTION 5 ?? I THOUGHT IT WAS C :,( please help

 

[tom850]

Just one tiny wincy question..WHY IS THE ANSWER A TO JANUARY 2010 QUESTION 5 ?? I THOUGHT IT WAS C :,( please help

Which Subject Eh

 

[Lost_Life]

Which Subject Eh

chemistry :'(

 

[tom850]

chemistry :'(

Aww Lemme Check :'(

 

[tom850]

chemistry :'(

Dun Cwy
The question says increasing boiling temperature and there are 3 gases!
You know the alkanes are saturated hydrocarbons and the boiling temperature increases as the chain increases.
Here CH4 is the Methane and it has the lowest boiling temperature of -164 oC
HCL, Hydrogen Chloride gas has the boiling temperature of -85 oC
HF, Hidrogen Flouride gas has the boiling temperature of 19.5 oC

Therefore, the answer is A CH4, HCL, HF

Does this help?
Or anyone else here to elaborate more?

 

[Lost_Life]

Dun Cwy
The question says increasing boiling temperature and there are 3 gases!
You know the alkanes are saturated hydrocarbons and the boiling temperature increases as the chain increases.
Here CH4 is the Methane and it has the lowest boiling temperature of -164 oC
HCL, Hydrogen Chloride gas has the boiling temperature of -85 oC
HF, Hidrogen Flouride gas has the boiling temperature of 19.5 oC

Does this help?
Or anyone else here to elaborate more?

ohhhhh .............. wow, think the stress caught up with my thinking..

 

[tom850]

ohhhhh .............. wow, think the stress caught up with my thinking..

Hehe Just take lil rests while doing the past papers ;D

 

[Lost_Life]

Hehe Just take lil rests while doing the past papers ;D

another q came up..

 

[tom850]

another q came up..View attachment 20003

Aww Yew Need Answer To This?
It is about ionic equation.

Sr2+(aq) + SO42− (aq) → SrSO4(s)

You have to write the state symbols as well if you want to get 2 marks;D
In perfect ionic equations, we don't have to show Na+ ions and Cl- ions as they are spectator ions and left out in the equation.

You want more help on this?

 

[Lost_Life]

nah

Aww Yew Need Answer To This?
It is about ionic equation.

Sr2+(aq) + SO42− (aq) → SrSO4(s)

You have to write the state symbols as well if you want to get 2 marks;D
In perfect ionic equations, we don't have to show Na+ ions and Cl- ions as they are spectator ions and left out in the equation.

You want more help on this?

nah, i figured it out a while ago... but thanks anyway

 

[tom850]

nah
nah, i figured it out a while ago... but thanks anyway

Hehe Owk:/ I will ask my doubts.. Em reading the notes now:'(

 

[Lost_Life]

Hehe Owk:/ I will ask my doubts.. Em reading the notes now:'(

okay

 

[Lost_Life]

unit 1 chemistry as-level june 2010 number 8

 

[tom850]

unit 1 chemistry as-level june 2010 number 8

Hey I even didnt know this The asnwer is D. But for me A is the right one
Im going through the notes to solve it

 

[Lost_Life]

i

Hey I even didnt know this The asnwer is D. But for me A is the right one
Im going through the notes to solve it

i thought it was C ? y'know? electrons leave the 3rd orbital first then 2nd then the first..3p 3s 2p 2s 1s

 

[tom850]

i
i thought it was C ? y'know? electrons leave the 3rd orbital first then 2nd then the first..3p 3s 2p 2s 1s

Hey.. you mean this question rite?

8. A sample of gas was prepared for use in helium-neon lasers. It contained 4 g of helium
and 4 g of neon. What is the ratio of helium atoms to neon atoms in the sample?
A 1 : 1
B 2.5 : 1
C 1 : 5
D 5 : 1

 

[Lost_Life]

Hey.. you mean this question rite?

8. A sample of gas was prepared for use in helium-neon lasers. It contained 4 g of helium
and 4 g of neon. What is the ratio of helium atoms to neon atoms in the sample?
A 1 : 1
B 2.5 : 1
C 1 : 5
D 5 : 1

nahh.. i get that..do you?

 

[tom850]

nahh.. i get that..do you?

Haha.. Naw :/ I didnt Can you tell me

This question is the one you asked :/

 

[Lost_Life]

Haha.. Naw :/ I didnt Can you tell me

This question is the one you asked :/

Moles = mass/ molar mass

sample------------------ Helium --------- Neon
Mass of sample----------4g --------------4g
Molar mass--------------4g/mol --------20.2g/mol
Mole ---------------------4/4------------ 4/20.2
----------------------------1 ----------------0.2

Divide by smallest-------- 1/0.2--------- 0.2/0.2

Ratio-------------------------------- 5 : 1

The answer is D

 

[tom850]

Moles = mass/ molar mass

sample------------------ Helium --------- Neon
Mass of sample----------4g --------------4g
Molar mass--------------4g/mol --------20.2g/mol
Mole ---------------------4/4------------ 4/20.2
----------------------------1 ----------------0.2

Divide by smallest-------- 1/0.2--------- 0.2/0.2

Ratio-------------------------------- 5 : 1

The answer is D

Aww ;D Thank Youh! Urgh.. I Did A Mistake :/
I was correct upto this level

Mole ---------------------4/4------------ 4/20.2
----------------------------1 ----------------0.2

But i forgot to divide by smallest. >.<
Hehe

Btw, it is the question you asked >> June 2010 Unit 1 question 8.
What is that electron question. I May Help ;D