Chemistry: Post your doubts here!

[Mishaa]

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5. C
Due to a significant difference between the 5th and 6th IEs, it can be deduced that X is in Group V of the periodic table with charge -3. It will mst probably form a covalent chloride XCl3.

28. B
Dissolving occurs due to hydrogen bonding between hydrogens or its isotopes that are directly bonded to oxygen, nitrogen or flourine, with water molecules. In this case, hydrogens directly bonded to oxygen are to be replaced, so apparently there would be 3 replacements.

3. C
At room temperature, post reaction gases are unreacted O2, CO2 and SO2. No need to take molar ratios, gaseus ratios are taken. 30 cm3 of O2 is left after reacton (30 cm3 reacts with 10cm3 of the thiol), 10 cm3 each of SO2 and CO2 are produced. Total is 50 cm3.

 

[Mishaa]

thanks sooo much
can u help me with this ?

Send me the links to the question papers, I can't read a word here. I'm sorry.

 

[ahmed abdulla]

Send me the links to the question papers, I can't read a word here. I'm sorry.

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w04_qp_1.pdf
q 10 , 12 , 18 & 37 38

 

[Student12]

http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_s07_qp_1.pdf
Q 9-A ( Please could someone elaborate & explain)26-C

http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_w07_qp_1.pdf
Q 9- B 10-D (How did the 2.42 come)

 

[Student12]

http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_s08_qp_1.pdf
Q 1D 2A 6C 15B 26C 31 2/3 are the right options.
http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_w08_qp_1.pdf
Q 1A 2C 4C 30C

 

[Student12]

I have a major problem in chemistry calculations.. how do i solve this problem? :/

 

[ahmed abdulla]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w04_qp_1.pdf
q 10 , 12 , 18 & 37 38

 

[Student12]

Someone answer!!

 

[h4rriet]

I have a major problem in chemistry calculations.. how do i solve this problem? :/

Practice questions.

 

[hela]

PLEASE HELP
http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_s08_qp_1.pdf Q6 C Q7 D Q26 C
http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_w08_qp_1.pdf Q 26 C
http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w10_qp_12.pdf Q 8 D Q25 D

 

[zackle09]

Hello! can someone pls do this for me
http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s10_qp_11.pdf

question 8...how do you solve it?

 

[Mairaxo]

Hello! can someone pls do this for me
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s10_qp_11.pdf

question 8...how do you solve it?

use all elements Ar given. Replace X using the elements given and find the mole ratio!

 

[Mairaxo]

PLEASE HELP
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s08_qp_1.pdf Q6 C Q7 D Q26 C
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w08_qp_1.pdf Q 26 C
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w10_qp_12.pdf Q 8 D Q25 D

May June 2008 - Q7 - Aluminium is a metal so metalic bond but phosphoros is a non metal and has covalent bonds so not A. Argon is monatomic and chlorine is diatomic so not B. Magnesium is a meta sulphur is non metal so different bonds. Sulphur and chlorine are both non metals with covalents bonds between atoms so its D

 

[Mairaxo]

PLEASE HELP
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s08_qp_1.pdf Q6 C Q7 D Q26 C
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w08_qp_1.pdf Q 26 C
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w10_qp_12.pdf Q 8 D Q25 D

May 2008 - Q26 - the alcohol is HO-CH2-CH2-CH2-CH2-OH. This is becaus only primary alcohols get oxidised to acids. secondry and tertiary alcohols dont. hence OH is at 1st and 4th carbon so its C.

 

[zackle09]

use all elements Ar given. Replace X using the elements given and find the mole ratio!

got it! thankss )

 

[SomeStudent]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s11_qp_11.pdf
16,22, 23, 25 to28 (would help a lot if someone gives me some general tips on how to solve org MCQs like the ones from 25 t0 28)
PLEASE! need the solutions quick.
Thank you so much!

 

[iKhaled]

can someone pls explain to me question 12 october nov 2010 paper 13

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w10_qp_13.pdf

 

[SomeStudent]

can someone pls explain to me question 12 october nov 2010 paper 13

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w10_qp_13.pdf

Energy released = mc(change in temp) 200x4.2x (66-18)=40230.
This is the total energy released which is 45% of the total energy released so 45% of x (supposed total energy)= 40230. Find x then divide it by 1.6.

 

[AbbbbY]

Some Doubts..
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s06_qp_1.pdfhttp://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s06_ms_1.pdf
Questions 1 , 3 , 10

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s07_qp_1.pdfhttp://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s07_ms_1.pdf Questions 8 , 9 , 26

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w07_qp_1.pdfhttp://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w07_ms_1.pdf Questions 1, 9 , 10

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s08_qp_1.pdfhttp://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s08_ms_1.pdf Questions 1,2,6,15,31

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w08_qp_1.pdfhttp://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w08_ms_1.pdfQuestions 1,2,4,30

I know these are aloot in one go.. but i need help! =)

ON07 Q10

2 : 2 : 1
Start: 4 : 0 : 0
Equilibrium: 2.4 : 1.6 : 0.8 [If you don't understand how these concentration values have been reached, ask!]

[Products]/[Reactants]
([0.8][1.6]^2)/[2.4]^2


MJ08

Q1

6CaO + P4O10 -> 2Ca3(PO4)2

So, D

2-

14g per 5dm3
so
2.8g per dm3

100g contains 15g N
2.8g will contain 0.42g of N

Conc: 0.42g/dm3
divide it by Ar to get mol/dm3
Hence, 0.03. So, A.

6-

15-

CaCO3 -> CaO + CO2

1200 ton = 1200/100 = 12mol [in terms of tonnes]
12*44 = 528 tonnes

Hence, B

31-

C2H5OH + 3O2 -> 2CO2 + 3H2O

Since 1 is wrong, it has to be C.

Just to check,
C2H2 + 5/2O2 -> 2CO2 + H2O

CH3CHO + 5/2O2 -> 2CO2 + 2H2O
And again, C.

 

[iKhaled]

can someone tell me how to solve these type of questions ? question 4 oct/nov 2009 paper 12

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w09_qp_12.pdf