Author Topic: CHEMISTRY PAPER 1 HERE  (Read 37923 times)

Offline esso

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Re: CHEMISTRY PAPER 1 HERE
« Reply #150 on: June 11, 2009, 02:54:51 pm »
nd one more question

which process can convert molecules to a new substance by removing hydrogen atoms
A displacement
B fermentation
C neutralisation
D oxidation

how do you solve this question
john it is oxidation By the way it is not der 4r us it cums in O-levels loss of hydrogen is oxidation


from which paper is this question ???

Offline aquarian93

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Re: CHEMISTRY PAPER 1 HERE
« Reply #151 on: June 11, 2009, 02:56:01 pm »
this is from may 05, if anyone has solved it, pls help me.
for question 16, the answer is D

y cnt it b C? pls help, thanks in advance

For 3, there would be no loss in mass, as any gas produced would remain inside the conical flask, and not be able to excape through the stopper.

yea bt if it dusnt escape, u can still use it cuz the mass will increase as gas is produced and wont escape. da mass will increase
rite?

Umm no, conservation of mass = mass of products is always equal to mass of reactants. So, to show the rate of reaction, a decrease in mass must occur.

ok so always a decrease in mass.
thanks alot :) +rep

Offline aquarian93

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Re: CHEMISTRY PAPER 1 HERE
« Reply #152 on: June 11, 2009, 02:57:39 pm »
and guys doesnt sodium oxide hav a pH above 7 (metal oxide)

den how cum the answer in nov 05, question 17 is C ???

Offline girl_92

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Re: CHEMISTRY PAPER 1 HERE
« Reply #153 on: June 11, 2009, 02:59:57 pm »
and guys doesnt sodium oxide hav a pH above 7 (metal oxide)

den how cum the answer in nov 05, question 17 is C ???
it bcums dilute pH is lowered
some people sleep to dream while othrs wakeup to follow dem im the second type how abt u

nid404

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Re: CHEMISTRY PAPER 1 HERE
« Reply #154 on: June 11, 2009, 03:01:20 pm »
and guys doesnt sodium oxide hav a pH above 7 (metal oxide)

den how cum the answer in nov 05, question 17 is C ???

Read the question correctly. Sodium oxide, when in solution it forms OH-ions which give the pH for the solution and changes pH of water(7) to 12
 Hence C

Offline aquarian93

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Re: CHEMISTRY PAPER 1 HERE
« Reply #155 on: June 11, 2009, 03:03:03 pm »
and guys doesnt sodium oxide hav a pH above 7 (metal oxide)

den how cum the answer in nov 05, question 17 is C ???
it bcums dilute pH is lowered

but pH has nothing to do wid water and dilute Sad
plus its a metal oxide, the pH has to be above 7.

nid404

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Re: CHEMISTRY PAPER 1 HERE
« Reply #156 on: June 11, 2009, 03:03:47 pm »
and guys doesnt sodium oxide hav a pH above 7 (metal oxide)

den how cum the answer in nov 05, question 17 is C ???
it bcums dilute pH is lowered

but pH has nothing to do wid water and dilute Sad
plus its a metal oxide, the pH has to be above 7.
Tell me what pH of water is

Offline aquarian93

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Re: CHEMISTRY PAPER 1 HERE
« Reply #157 on: June 11, 2009, 03:04:31 pm »
and guys doesnt sodium oxide hav a pH above 7 (metal oxide)

den how cum the answer in nov 05, question 17 is C ???

Read the question correctly. Sodium oxide, when in solution it forms OH-ions which give the pH for the solution and changes pH of water(7) to 12
 Hence C

oh so da sodium oxide is added to the water. omg, stupid me
thanks nid :) as always, i say thanks to u, haha
+rep

Offline girl_92

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Re: CHEMISTRY PAPER 1 HERE
« Reply #158 on: June 11, 2009, 03:04:46 pm »
and guys doesnt sodium oxide hav a pH above 7 (metal oxide)

den how cum the answer in nov 05, question 17 is C ???

Read the question correctly. Sodium oxide, when in solution it forms OH-ions which give the pH for the solution and changes pH of water(7) to 12
 Hence C
yea srry i rote it according to tht sodium i didnt read the que properly
some people sleep to dream while othrs wakeup to follow dem im the second type how abt u

Offline girl_92

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Re: CHEMISTRY PAPER 1 HERE
« Reply #159 on: June 11, 2009, 03:06:34 pm »
can sum1 explain this que plz
Please help.....O/N 2007, paper 1, Q11
some people sleep to dream while othrs wakeup to follow dem im the second type how abt u

....

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Re: CHEMISTRY PAPER 1 HERE
« Reply #160 on: June 11, 2009, 03:07:06 pm »
Please help.....O/N 2007, paper 1, Q11
please explain, thanks in advance...

For this, you have to form a balanced equation for the combustion of each of them. The one that forms a balanced equation with 8O2 is the correct one.
The answer is B, because...

C6H9OH  +  8O2  -----> 6CO2  +  5H2O

You can form a balanced equation with B, so B is the answer

Offline girl_92

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Re: CHEMISTRY PAPER 1 HERE
« Reply #161 on: June 11, 2009, 03:08:30 pm »
Please help.....O/N 2007, paper 1, Q11
please explain, thanks in advance...

For this, you have to form a balanced equation for the combustion of each of them. The one that forms a balanced equation with 8O2 is the correct one.
The answer is B, because...

C6H9OH  +  8O2  -----> 6CO2  +  5H2O

You can form a balanced equation with B, so B is the answer
Thanks but i think der is sumtin more to it
some people sleep to dream while othrs wakeup to follow dem im the second type how abt u

....

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Re: CHEMISTRY PAPER 1 HERE
« Reply #162 on: June 11, 2009, 03:10:32 pm »
Please help.....O/N 2007, paper 1, Q11
please explain, thanks in advance...

For this, you have to form a balanced equation for the combustion of each of them. The one that forms a balanced equation with 8O2 is the correct one.
The answer is B, because...

C6H9OH  +  8O2  -----> 6CO2  +  5H2O

You can form a balanced equation with B, so B is the answer
Thanks but i think der is sumtin more to it

Hmm, like?
The main thing is that, only one molecule of each organic compound is to be used in your equation.

Offline girl_92

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Re: CHEMISTRY PAPER 1 HERE
« Reply #163 on: June 11, 2009, 03:12:55 pm »
Please help.....O/N 2007, paper 1, Q11
please explain, thanks in advance...

For this, you have to form a balanced equation for the combustion of each of them. The one that forms a balanced equation with 8O2 is the correct one.
The answer is B, because...

C6H9OH  +  8O2  -----> 6CO2  +  5H2O

You can form a balanced equation with B, so B is the answer
Thanks but i think der is sumtin more to it

Hmm, like?
no i think its f9 may be dey want us to actually sit n balance
anywayz Thanks
some people sleep to dream while othrs wakeup to follow dem im the second type how abt u

....

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Re: CHEMISTRY PAPER 1 HERE
« Reply #164 on: June 11, 2009, 03:13:40 pm »
Please help.....O/N 2007, paper 1, Q11
please explain, thanks in advance...

For this, you have to form a balanced equation for the combustion of each of them. The one that forms a balanced equation with 8O2 is the correct one.
The answer is B, because...

C6H9OH  +  8O2  -----> 6CO2  +  5H2O

You can form a balanced equation with B, so B is the answer
Thanks but i think der is sumtin more to it

Hmm, like?
no i think its f9 may be dey want us to actually sit n balance
anywayz Thanks
No problem at all!