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ANSWERING ALL BIO/CHEM PAPER 1 DOUBTS :)

A

Ahmed Khider

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ZainH said:
Lots of questions.. this paper:http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_w07_qp_1.pdf

Q.7,9,11,24,35

A small explanation please.. I'm terriBAD at chemistry.
Click to expand...
In qno 7 u know that a covalent bond is between 2 or more non metals. In this question we have 3 non metals X,Y and Z. However Z is a noble gas and it is unreactive so the answer has to be C.
In qno 9 we should a salt so the answer is either A or D. However Barium Sulphate is insoluble in water so there is no point of adding it becoz it would not dissolve in the water so the answer is D.
In qno 11 its just a matter of balancing try all these compunds and one of them will give u 8 molecules of Oxygen when u balance it correctly which is B.
In qno 24 X displaces Y from its compund so it has to be more reactive than it and in group 7 the reactivity increases upwards so the answer is B because chlorine is more reactive than iodine.
In qno 35 the positive charged ions are Sodium, Potassium, Magnesium and Calcium. From these 4 only Potassium and Sodium are in group 1 so their valencies are +1..so adding their masses 6.5+1 u will get 7.5 so the answer is A.
 
ZainH

ZainH

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сᴏᴏʟ сяуѕтᴀʟѕ said:
Assalam-o-alaikum wr wb...
Q7) covalent bond is formed when 2 non metals combine..the 2 nonmetals in that case are only X and Y!
Q9) If he adds the first 3 substances, the reaction will not take place bcoz they are insoluble in water..so the only possibility is D as it is soluble.
Q11) You need to write a balanced equation for this reaction...
write for all..and you will know that the answer is B bcoz..
C6H9OH + 8O2 = 6CO2 + 5H2O
it shows that one molecule of the organic compound, needs 8 molecules of Oxygen, so the answer is B!

sorry i don't have time so can't explain the rest 2..seriously sorry!
Click to expand...
Ahmed Khider said:
In qno 7 u know that a covalent bond is between 2 or more non metals. In this question we have 3 non metals X,Y and Z. However Z is a noble gas and it is unreactive so the answer has to be C.
In qno 9 we should a salt so the answer is either A or D. However Barium Sulphate is insoluble in water so there is no point of adding it becoz it would not dissolve in the water so the answer is D.
In qno 11 its just a matter of balancing try all these compunds and one of them will give u 8 molecules of Oxygen when u balance it correctly which is B.
In qno 24 X displaces Y from its compund so it has to be more reactive than it and in group 7 the reactivity increases upwards so the answer is B because chlorine is more reactive than iodine.
In qno 35 the positive charged ions are Sodium, Potassium, Magnesium and Calcium. From these 4 only Potassium and Sodium are in group 1 so their valencies are +1..so adding their masses 6.5+1 u will get 7.5 so the answer is A.
Click to expand...

Thanks a ton guys, I just forgot to check for a reply before the paper. But it still went amazing, thanks for the help x)
 
svenas

svenas

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сᴏᴏʟ сяуѕтᴀʟѕ said:
Assalam-o-alaikum wr wb...
Q7) covalent bond is formed when 2 non metals combine..the 2 nonmetals in that case are only X and Y!
Q9) If he adds the first 3 substances, the reaction will not take place bcoz they are insoluble in water..so the only possibility is D as it is soluble.
Q11) You need to write a balanced equation for this reaction...
write for all..and you will know that the answer is B bcoz..
C6H9OH + 8O2 = 6CO2 + 5H2O
it shows that one molecule of the organic compound, needs 8 molecules of Oxygen, so the answer is B!

sorry i don't have time so can't explain the rest 2..seriously sorry!
Click to expand...
hiiii.hw was ur paper....me was ok I got sme mistakes ...wat u wrote for question about polymer PVC functional group...I wrote it will have both
 
сᴏᴏʟ сяуѕтᴀʟѕ

сᴏᴏʟ сяуѕтᴀʟѕ

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svenas said:
hiiii.hw was ur paper....me was ok I got sme mistakes ...wat u wrote for question about polymer PVC functional group...I wrote it will have both
Click to expand...
my paper was good Alhamdulillah..but made 2 silly mistakes :( so expecting till 38 INshallah...

umm...was that question number 34 or 38? i mean what were the options...chose b/w alkanoic acid, alkene and alcohol OR alcohol and alkene? :eek:

for the alkanoic acid...it was alkene and alkanoic acid but not alcohol.. (question 34)

for question 38...it was both...alkene and alcohol!
 
сᴏᴏʟ сяуѕтᴀʟѕ

сᴏᴏʟ сяуѕтᴀʟѕ

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ZainH said:
Thanks a ton guys, I just forgot to check for a reply before the paper. But it still went amazing, thanks for the help x)
Click to expand...
Assalam-o-alaikum wr wb..
Your welcome...and really sorry..actually i completely forgot that i have an exam :p i was sorta late for it so had to run :oops: :ROFLMAO:
 
svenas

svenas

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сᴏᴏʟ сяуѕтᴀʟѕ said:
my paper was good Alhamdulillah..but made 2 silly mistakes :( so expecting till 38 INshallah...

umm...was that question number 34 or 38? i mean what were the options...chose b/w alkanoic acid, alkene and alcohol OR alcohol and alkene? :eek:

for the alkanoic acid...it was alkene and alkanoic acid but not alcohol.. (question 34)

for question 38...it was both...alkene and alcohol!
Click to expand...

yea me 2 I really made 2 silly mistakes in 2 repeated questions question 3 and question about co2 and o2 higher in planet...
Though I've solved them before bioo exam..and forgot that oxygen is 20%..don't know wat happened to me....the most thng which annoys me is the question about the oxygen and co2.....btw inshalla we will get A* ...can u plz grade my subjects in the thread I made befor like 30 min...check it plz...I'll be glad to hear ur reply...
bye and tell me wat u will do in holidays...will u travel?
 
сᴏᴏʟ сяуѕтᴀʟѕ

сᴏᴏʟ сяуѕтᴀʟѕ

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svenas said:
yea me 2 I really made 2 silly mistakes in 2 repeated questions question 3 and question about co2 and o2 higher in planet...
Though I've solved them before bioo exam..and forgot that oxygen is 20%..don't know wat happened to me....the most thng which annoys me is the question about the oxygen and co2.....btw inshalla we will get A* ...can u plz grade my subjects in the thread I made befor like 30 min...check it plz...I'll be glad to hear ur reply...
bye and tell me wat u will do in holidays...will u travel?
Click to expand...
awwh..it's okie! Inshallah we all will get straight A*s !
now we can do nothing...other than pray to Allah bcoz it's no use crying over split milk :p

sure...i will see it, Inshallah...
yeahp...Inshallah i will! wbu?
 
сᴏᴏʟ сяуѕтᴀʟѕ

сᴏᴏʟ сяуѕтᴀʟѕ

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Ahmed Khider said:
Are u kidding?? U must hve been really nervous!!!
Click to expand...
nope...m serious! i was VERY nervous....actually i even forgot to check the 'last minute revision questions' (which i posted yesterday)...did not solve paper 2011...and the driver was waiting outside for me :p
i dowloaded all of them on my cell...and did it in the skool :p
 
A

Ahmed Khider

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сᴏᴏʟ сяуѕтᴀʟѕ said:
nope...m serious! i was VERY nervous....actually i even forgot to check the 'last minute revision questions' (which i posted yesterday)...did not solve paper 2011...and the driver was waiting outside for me :p
i dowloaded all of them on my cell...and did it in the skool :p
Click to expand...
Lol..i know how u feel..i missed an exam b4 :(..i totally 4got i had the exam
 
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