Chemistry: Post your doubts here!

[Alice123]

Q39
ok here goes you see the 3 options given right? look closely at the 3rd option.. umm just open the file attached, it should make sense.. if it doesnt all you have to do is ask

Thankyou sooooooooooooooooooooooooooooooooooo much !!! your explanation is quite clear...

 

[Jiyad Ahsan]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w12_qp_13.pdf Q26

Okay thing about Q 26 is you have to form reaction intermediates right?
i'm going to focus on why B (W and Y) is the correct answer.
W = CH3CH2CH3
Y = CH3CH=CH2

with W you react it with Br2 and you get a bromo-alkane with 3 carbons,
same as when you react Y with HBr you get the same bromo-alkane..

if you want more explanation regarding anything.. please ask,
sorry i'm feeling a bit too lazy to do all the working

 

[Jiyad Ahsan]

Thankyou sooo much
i did understand
Best of luck fr yr exam



Thanks

Thankyou sooooooooooooooooooooooooooooooooooo much !!! your explanation is quite clear...

no prob and thnx best of luck to you too

 

[kingos3111]

k wat abt oct nov 2004 q31

 

[kingos3111]

k wat abt very imp may june 2007 q9

 

[kingos3111]

nd pleaseeeeeeee may june 2006 q1

 

[ShaanSiddiq090909]

9701_w09_qp_11.pdf
please explain q 40 someone!!

 

[ShaanSiddiq090909]

can u help with this bro

9701_w09_qp_11.pdf
please explain q 40 someone!!
Bro plz explain q 40#

 

[ahmed abdulla]

9701_w09_qp_11.pdf
please explain q 40 someone!!
Bro plz explain q 40#

looking at first choice .. it says its saturated (no double bond-alkane) and diol ( 2 OH group)
it has 4 carbon ,, you know alkane with 4 carbon (butane) has formula C4H8 ..
in this case replace 2 hydrogen with OH group (since its diol)
this gives you C4H6 (OH)2 which has molecular formula of 90 ...
since one is wrong ... answer is C

 

[A star]

what do you guys consider a safe score :/

 

[strangerss]

density = mass/ volume , so mass will be density multiply by volume.. and volume was in cm^3 so convert it to dm3... but if u dont want to, anyways u'll have to divide it by 1000 to change grams into kilograms..

oh ok thanks , so the ideal gas equation can actually be used for any gas ?

 

[strangerss]

density = mass/ volume , so mass will be density multiply by volume.. and volume was in cm^3 so convert it to dm3... but if u dont want to, anyways u'll have to divide it by 1000 to change grams into kilograms..

oh ok thanks , so the ideal gas equation can actually be used for any gas ?

 

[ShaanSiddiq090909]

9701_s09_qp_1.pdf
q 40 someone pleaseee explaainn!!

 

[Alice123]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w09_qp_11.pdf Q21
Jiyad Ahsan daredevil littlecloud11 A star syed1995 PANDA- please

 

[Aymen Ezazi]

oh ok thanks , so the ideal gas equation can actually be used for any gas ?

yes it can be..

 

[Aymen Ezazi]

9701_s09_qp_1.pdf
q 40 someone pleaseee explaainn!!

the bond will be broken from CO2 thats where the Na from NaOH will bond to oxygen.. it will not be 3 bcoz they have taken out the alkene completely so its wrong.. 2 is correct bcoz Na is bonded to O and the rest of the molecule is ok.. so definetly its going to be 1 also.. bcoz there is no option just for 2.. but u can still check it.. see if all the bonds are presnt or not and with OH which comes from NaOH

 

[A star]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w09_qp_11.pdf Q21
Jiyad Ahsan daredevil littlecloud11 A star please

C?

 

[Alice123]

C?

A

 

[ShaanSiddiq090909]

the bond will be broken from CO2 thats where the Na from NaOH will bond to oxygen.. it will not be 3 bcoz they have taken out the alkene completely so its wrong.. 2 is correct bcoz Na is bonded to O and the rest of the molecule is ok.. so definetly its going to be 1 also.. bcoz there is no option just for 2.. but u can still check it.. see if all the bonds are presnt or not and with OH which comes from NaOH

Thanks .. but can you explain it a bit more coz I still didn't understand why did the bond from CO2 break!

 

[Aymen Ezazi]

Thanks .. but can you explain it a bit more coz I still didn't understand why did the bond from CO2 break!

bcoz the only electronegative atom in this molecule is O, so Na can bond only to oxygen and no other atom..