Troubles in chem p1

[cute97]

heeey guys I have a problem while doing past papers and everytime I lose from 15 to 20 marks do u think it is a lot ?? umm is there anyone who can help me
thanks in advance

 

[angel456]

just try to make some notes on the questions u get wrong and give them quick revision everytym u sit to do chem past papers it will surley help
btw the questns u get wrong surf the internet or ur notes to get sum help........ i hope it will help u[/quote]

 

[anishniroula]

heeey guys I have a problem while doing past papers and everytime I lose from 15 to 20 marks do u think it is a lot ?? umm is there anyone who can help me
thanks in advance

same here dude.. I get just 20-25 correct. But practise more.. You will get more correct.

 

[A star]

heeey guys I have a problem while doing past papers and everytime I lose from 15 to 20 marks do u think it is a lot ?? umm is there anyone who can help me
thanks in advance

i loose nearly 8 marks in phy and 5 marks in chem
Just see whether you cannot understand the answers or you are making silly errors :/

 

[sorrows]

 

[Manahil Shafiq]

i start messing up when organic part starts....i guess i've developed organic phobia

 

[cute97]

i loose nearly 8 marks in phy and 5 marks in chem
Just see whether you cannot understand the answers or you are making silly errors :/

Mashallah i think my problem is in the calculations and the last 10 questions and yhh some silly errors but these are hardly 2 or 3

 

[cute97]

just try to make some notes on the questions u get wrong and give them quick revision everytym u sit to do chem past papers it will surley help
btw the questns u get wrong surf the internet or ur notes to get sum help........ i hope it will help u

[/quote]

i really don't knw to which topics these are related. mostly in the calculations thingies and i dont get alot of help online

 

[sufyanalizaib]

Use of the Data Booklet is relevant to this question.
When 3.00 g of an anhydrous nitrate of a Group II metal is decomposed, 1.53 g of gas is
produced.
What is the nitrate compound?
A beryllium nitrate
B calcium nitrate
C magnesium nitrate
D strontium nitrate help plz

 

[cute97]

Use of the Data Booklet is relevant to this question.
When 3.00 g of an anhydrous nitrate of a Group II metal is decomposed, 1.53 g of gas is
produced.
What is the nitrate compound?
A beryllium nitrate
B calcium nitrate
C magnesium nitrate
D strontium nitrate help plz

same doubt here anyone answer plzzz !!

 

[cute97]

Anyone here to help me with these pls
http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_w05_qp_1.pdf
Q16, Q17 what do they mean by ligand here ?? Q24, Q30 the answer is hydrolysis but its not condensation polymerisation and if it is condensation how did u knw?? and Q32 what is planer here ??
Thank you in advance

 

[Jinkglex]

I know this sounds long and tedious, but the sure-shot way would be for you to calculate the MR of all the mentioned nitrates, divide 3 grams on each to see the number of moles it would represent, and then see if said nitrates decomposition product [lets call it XO] fits the bill, as it will have the same number of moles, and if 1.53 is the answer you get [by multiplying the number of moles mentioned previously with the MR of the decomposition product], there's your answer.

same doubt here anyone answer plzzz !!

 

[Jinkglex]

Anyone here to help me with these pls
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w05_qp_1.pdf
Q16, Q17 what do they mean by ligand here ?? Q24, Q30 the answer is hydrolysis but its not condensation polymerisation and if it is condensation how did u knw?? and Q32 what is planer here ??
Thank you in advance

for future reference, if you could throw in the answer key with the paper link, it would be quite helpful

16 would be C because of the keyword "effervescence", something you should almost always associate with CO2. We got the initial eff. because of CO3 in BaCO3 decomposing, as it is highly polarized, and then the second time with CaCO3, as the CO3 there is less polarized

17 is B but if you are AS dont worry, ligands are no longer a part of your syllabus.

24 draw the structure of each, and then form a C=C bond in all the possibilities for each one.

30 is hydrolysis....because the repeat unit is made in the question and it is said "made from sugars"

32 is D because BCl3 is the only one with 3 bond pairs no lone pairs...the others have lone pairs causing shape distortion

 

[1357913579]

http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_s09_qp_1.pdf
can somebody please help in this
number-28 iam getting answer as (d) but the ms says (c) why?
iam getting 3 ketons and 1 aldehyde

 

[Jinkglex]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s09_qp_1.pdf
can somebody please help in this
number-28 iam getting answer as (d) but the ms says (c) why?
iam getting 3 ketons and 1 aldehyde

i believe only 3 are made because, as you can see, the question says 9 carbon atoms must remain in the end.
So if you look at the far right side, you'll see a double bond with a CH3 attached. Heating with conc. K2Cr2O7 will indeed introduce OH to both C=C bonds present in the molecule, but you may only dispatch one of them, and i believe it will be 3 ketones, 0 aldehydes

Also: the aldehyde, even if formed, will be converted straight to carboxylic acid as no quick method of extraction is stated, so your answer would be wrong regardless.

 

[1357913579]

i believe only 3 are made because, as you can see, the question says 9 carbon atoms must remain in the end.
So if you look at the far right side, you'll see a double bond with a CH3 attached. Heating with conc. K2Cr2O7 will indeed introduce OH to both C=C bonds present in the molecule, but you may only dispatch one of them, and i believe it will be 3 ketones, 0 aldehydes

Also: the aldehyde, even if formed, will be converted straight to carboxylic acid as no quick method of extraction is stated, so your answer would be wrong regardless.

oh yeah thanks bro i forgot actually aldehyde would be formed iam attaching a file but then i forgot its HOT conc acidified lmno4 so it will further oxidse to carboxylic acid

 

[cute97]

for future reference, if you could throw in the answer key with the paper link, it would be quite helpful

16 would be C because of the keyword "effervescence", something you should almost always associate with CO2. We got the initial eff. because of CO3 in BaCO3 decomposing, as it is highly polarized, and then the second time with CaCO3, as the CO3 there is less polarized

17 is B but if you are AS dont worry, ligands are no longer a part of your syllabus.

24 draw the structure of each, and then form a C=C bond in all the possibilities for each one.

30 is hydrolysis....because the repeat unit is made in the question and it is said "made from sugars"

32 is D because BCl3 is the only one with 3 bond pairs no lone pairs...the others have lone pairs causing shape distortion

Thank you. Sry but am a bad in chem for 16 BaCo3 is highly polar this is why its the answer ?? wat abt CaCo3 and why you dont choose the other carbonates ??
in 24 yhh i did but for butan-2-ol the correct answer i got only 2 places for double bond and the question says 3 alkenes.

 

[Jinkglex]

oh damn sorry, i meant CaCO3 is higher polarized, and BaCO3 is less polarized**

and it doesnt matter if you are good or bad in chem, we all get better with practice

 

[Jinkglex]

Thank you. Sry but am a bad in chem for 16 BaCo3 is highly polar this is why its the answer ?? wat abt CaCo3 and why you dont choose the other carbonates ??
in 24 yhh i did but for butan-2-ol the correct answer i got only 2 places for double bond and the question says 3 alkenes.

are you in AS, or A2? that'll help in answering your questions better.

 

[cute97]

are you in AS, or A2? that'll help in answering your questions better.

AS