Biology; Chemistry; Physics: Post your doubts here!

[Snowysangel]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_s12_qp_11.pdf
Q.34. How is it 3? :/
And 37 also

Isn't 37 c?? What is it?

 

[Ishrar Afrida]

Isn't 37 c?? What is it?

I know it is C, but how?
And could you do no. 40?

 

[Snowysangel]

I know it is C, but how?
And could you do no. 40?

The hydrocarbon and the total golyme of products are in a ratio 1:7. for 1 mole of the hydrocarbon, the total vilume of the products (both water and co2) is 7 moles, so the answers c. Is 40 A?

 

[Ishrar Afrida]

No, 40 is C. Very confusing..
And thanks for help

The hydrocarbon and the total golyme of products are in a ratio 1:7. for 1 mole of the hydrocarbon, the total vilume of the products (both water and co2) is 7 moles, so the answers c. Is 40 A?

 

[Snowysangel]

Could someone please answer this. Why are alternate carbons bonded to ch3 groups in the structure of polypropene?

 

[asma tareen]

SIS UR QUESTIONS KEEP ON SCARIN ME
tag me if yuh get yo ans

 

[Saad Mughal]

Could someone please answer this. Why are alternate carbons bonded to ch3 groups in the structure of polypropene?

The CH3 or Methyl group is attached alternatively in many ways in the polymer, it affects the melting point and crystalline structure of the polymer.
If you are asking why, then consider the monomer, i.e. propene, it has a carbon-carbon double bond with 3 hydrogen atoms and a methyl group attached, when the polymer forms (by addition), there is a series of propene molecules that add up to each other, this forms a single horizontal carbon chain connected to hydrogen and methyl group alternatively. Here's a picture of how propene is drawn to form a polymer.

 

[Snowysangel]

The CH3 or Methyl group is attached alternatively in many ways in the polymer, it affects the melting point and crystalline structure of the polymer.
If you are asking why, then consider the monomer, i.e. propene, it has a carbon-carbon double bond with 3 hydrogen atoms and a methyl group attached, when the polymer forms (by addition), there is a series of propene molecules that add up to each other, this forms a single horizontal carbon chain connected to hydrogen and methyl group alternatively. Here's a picture of how propene is drawn to form a polymer.
View attachment 26150

What if there's no alkyl group attached to the monomer?

 

[Saad Mughal]

Also, could someone please post all the procedures of the industrial processes

There are quite a few, which book do you have?

 

[Saad Mughal]

What if there's no alkyl group attached to the monomer?

That's not possible for propene, the reason is that unless the monomer structure is like the picture I posted above, the polypropene CANNOT form since a repeat structure would not be formed.

 

[Snowysangel]

There are quite a few, which book do you have?

Chem insight and this other book but the second one isn't useful at all

 

[Saad Mughal]

Chem insight and this other book but the second one isn't useful at all

Oh, I don't have insights; I'll post the procedures after tomorrow's paper.

 

[Snowysangel]

That's not possible for propene, the reason is that unless the monomer structure is like the picture I posted above, the polypropene CANNOT form since a repeat structure would not be formed.

Does polymethene exist? So if the unsaturated hydrocarbon doesn't have an alkyl group, it can't have a repeat unit? What if the repeat unit is h-c-h-h-?

 

[Snowysangel]

Oh, I don't have insights; I'll post the procedures after tomorrow's paper.

Okay thanks

 

[Saad Mughal]

Does polymethene exist? So if the unsaturated hydrocarbon doesn't have an alkyl group, it can't have a repeat unit? What if the repeat unit is h-c-h-h-?

Methene doesn't exist so how can Polymethene exist?
Unsaturated hydrocarbons from propene onwards need an alkyl group to form polymers.
The repeat unit, has to be the single molecule of the substance.

 

[Al-Anoud]

hello ppl! if the questions asks us to state ohm's law, do we just right R=V/I? or r we supposed to explain something? (the question was for 2 marks for some reason) :s (IGCSE physics btw)

 

[Saad Mughal]

hello ppl! if the questions asks us to state ohm's law, do we just right R=V/I? or r we supposed to explain something? (the question was for 2 marks for some reason) :s (IGCSE physics btw)

Ohm's law states that at constant temperature and pressure, all ohmic conductors' voltage is directly propotional to the current (i.e. R=V/I), where R is the constant/resistance.

 

[Al-Anoud]

Ohm's law states that at constant temperature and pressure, all ohmic conductors' voltage is directly propotional to the current (i.e. R=V/I), where R is the constant/resistance.

ook! thnxx alot bro...wow...amazing definition...

 

[Al-Anoud]

http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Physics (0625)/0625_w10_qp_33.pdf
u guys...Q.10 part (a) please...ts really difficult....nd the amazing examiners didnt know how to phrase it in the mark scheme...:|

 

[Sparky123]

http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Physics (0625)/0625_w10_qp_33.pdf
u guys...Q.10 part (a) please...ts really difficult....nd the amazing examiners didnt know how to phrase it in the mark scheme...:|

MashaAllah, I did it:
Q.10(a) draw R equidistant to surface to S
measure radii of each wave and draw around R the portion going beyond reflecting surface, to left.