Chemistry: Post your doubts here!

[saudha]

do you know have any concept about diagonal relationship of periodic table...???

i just googled it...thxx for the info

 

[étudiante]

i just googled it...thxx for the info

ur welcum

 

[Casablanca]

i just googled it...thxx for the info

In the past paper you're doing, do you know the answer for 14? The question about the graph of acidity of period 2 oxides. Is the answer A or B? (or something else?)

 

[Afeef]

Use of the Data Booklet is relevant to this question.
Which element is likely to have an electronegativity similar to that of aluminium?
A barium
B beryllium
C magnesium
D strontium
why is it B....how?

I remember my Chemistry teacher told me that right adjacent elements share much of the same properties, so only beryllium is on right side of aluminium

 

[Soulgamer]

I remember my Chemistry teacher told me that right adjacent elements share much of the same properties, so only beryllium is on right side of aluminium

Diagonal relationship.
Due to similar ionic radii, Be and Al have same chemical properties, Li and Mg also have diagonal relationship as-well.

 

[hmlahori]

Can someone please explain these paper 1 questions?
Thanks.....

http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_w11_qp_11.pdf
http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_w11_ms_11.pdf
Q8 Why cant the answer be C?
Q16?
Q27 Why is the ratio 3:1?
Q36?

And why isnt the examiner report for this paper available here?

 

[Muhammad Bin Anis]

someone please help in the following questions
june 2007, p1 . Q 34, 36, 37
nov 2007, p1, q35

 

[Anoushay]

its a mattr of balncin da equation..
5HIO----> 2I2+ 1HIO3+ 2H2o

ANS: B

thanks, so they have written oxidation number to confuse us?

 

[Anoushay]

5 HIO = 2 I2 + HIO3 + 2 H2O

thanks but can you explain why is this the answer?

 

[xxfarhaxx]

thanks, so they have written oxidation number to confuse us?

wel yes..u knw hw CIE is!!!

 

[xxfarhaxx]

someone please help in the following questions
june 2007, p1 . Q 34, 36, 37
nov 2007, p1, q35

june / 07-
Q 37 coz
1. energy is hs to b takn in to brk da bond, thrf endothermic
2. activation energy is high cz stng bnds btween N2..
3 N2 had tripl bonds. so bond energy is high!!!
ANS: A

 

[smartangel]

http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_w09_qp_12.pdf
please explain Q40!!

 

[saudha]

In the past paper you're doing, do you know the answer for 14? The question about the graph of acidity of period 2 oxides. Is the answer A or B? (or something else?)

B

 

[saudha]

A monomer undergoes addition polymerisation. A 1 mol sample of the monomer is completely
polymerised.
How many moles of polymer might, theoretically, be formed?
1.1
2 .10–6
3.6.02 1023(avogadro's constant)

 

[leosco1995]

A monomer undergoes addition polymerisation. A 1 mol sample of the monomer is completely
polymerised.
How many moles of polymer might, theoretically, be formed?
1.1
2 .10–6
3.6.02 1023(avogadro's constant)

If 1 mole of a monomer is polymerized and you obtained the same number of moles of a polymer, then technically... you got the same thing right? So 1 can't be a polymer. 2 and 3 are just random numbers given but they can be polymers because they're not the same # of moles as the monomer.

So C is right.

 

[Casablanca]

B

Thanks.

 

[Oliveme]

Can someone please explain these paper 1 questions?
Thanks.....

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w11_qp_11.pdf
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w11_ms_11.pdf
Q8 Why cant the answer be C?
Q16?
Q27 Why is the ratio 3:1?
Q36?

And why isnt the examiner report for this paper available here?

8) because acids give away H+ ions not gain them. look at the backward reaction in equation 2.

27) ultraviolet light means a free radical reaction takes place and this involves HOMOLYTIC fission. Then there are 6 places from where Cl can attack the H to form 1-chloro-propane but only 2 places for attack to form 2-chloro-propane. Thus the 3:1 ratio.

Hope this helps. Good Luck.

 

[hmlahori]

Have some doubts....

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w11_qp_11.pdf
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w11_ms_11.pdf
Q16 I'm confused between options B & C. Clarify why its B.
Q36 The non-metallic element has to be nitrogen. It satisfies all the conditions in the question and the statements 1 & 2. But how is nitrogen dioxide polar?

 

[smartangel]

please tell me how to do this question..i dont knw how many times i"ve posted it! but no one has answered it yet
its Q 22 of jun11/11 if you need to refer to the paper. answer is A. PLEASE HELP ME OUT!!

 

[sumaiyarox:)]

y dos the bond length increase btween hydrogen chloride,hydrogen bromide and hydrogen iodide?