P1 MCQ's preparation thread for chemistry ONLY!!!!

[sagystu]

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

i could explain the wo8 :20

from the formula or the name u could tell that the reactants are C6H5CH2CO2H and C2H5OH
so the phynyle bromine needs to add 1 carbon atom by nucleophicilic addition with CN- ions then converted to an acid by reaction with dtrong acid , the resulting carboxilic acid is reacted with C2H5OH to produce ester.

hope i helped

 

[sagystu]

ahmed abdulla sorry i didn't answer ur question i didn't see it.

KWIKIW thank u for answering my question

 

[sagystu]

I am a bit confused in (3) qs
(3) Why can't A be the correct answer?
It's difficult for me to choose between A and B.

it can't be A cause a u will have to remove 2 electrons '' 2 ionisations energy '' before u need to remove a one from a lower orbital , if it were A then the 3rd ionisation energy would be higher than others

 

[ahmed abdulla]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w04_qp_1.pdf
q 10
h4rriet

 

[fishcook]

Q12 Which chlorine compound has bonding that can be described as ionic with some covalent
character?
A NaCl B MgCl2 C AlCl3 D SiCl4

why is the answer B and not C??

 

[Mairaxo]

Q12 Which chlorine compound has bonding that can be described as ionic with some covalent
character?
A NaCl B MgCl2 C AlCl3 D SiCl4

why is the answer B and not C??

AlCl3 is more covalent than ionic. MgCl2 is ionic with some covalent. Got the difference?

 

[fishcook]

AlCl3 is more covalent than ionic. MgCl2 is ionic with some covalent. Got the difference?

oooh, yupp i got it
thank you

 

[Mairaxo]

oooh, yupp i got it
thank you

lol ur welcome

 

[fishcook]

http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_s08_qp_1.pdf
Q6 and 8.
help please

 

[Mairaxo]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s08_qp_1.pdf
Q6 and 8.
help please

Q6 i found mass 1st. mass = density * volume. u get 1g. then find mole. 1/18. thn use PV=nRT . I got 2.7 tho. but its near almost

 

[Mairaxo]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s08_qp_1.pdf
Q6 and 8.
help please

Q8- D is most suitable because its directly proportional. B and C hav PV so its not applied there i guess. And in A i think it should be a curve downwards not straight line!

 

[fishcook]

Q6 i found mass 1st. mass = density * volume. u get 1g. then find mole. 1/18. thn use PV=nRT . I got 2.7 tho. but its near almost

Q8- D is most suitable because its directly proportional. B and C hav PV so its not applied there i guess. And in A i think it should be a curve downwards not straight line!

thanks a lot

 

[Mairaxo]

thanks a lot

no problem

 

[sagystu]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w07_qp_1.pdf

w07: 9 (b) , 10(d), could some one help ?

 

[A n g e l a ♥]

Q13,20,35 S09
Q1 W08
please =D

 

[Alool]

can someone help me in this question with explanation

 

[h4rriet]

hEy im having serious problms in Chem oct/nov 2010 varient 12 ........Q:39,38,33,29,27,26,25,13,11,8,4 .....kindly hlp

4. Use (bonds broken - bonds formed).
8. You have to draw a Hess cycle:

11. You have to draw an ICE chart, i.e. initial concentrations, change in concentrations and equilibrium concentration. Then work out the final concentrations and from that work out the Kc.
13. The number of electrons lost by I must = the number of electrons gained. All you have to do is balance the oxidation numbers on either side of the equation.
25. Reaction A is cracking and need high temperatures and pressures, reactions B and C need reflux. That leaves D. D is, by the way, 2,4-DNP with a carbonyl compound.
26. B. An aldehyde will get oxidised by a Tollens' reagent.
27. The compound shown is an ester. It'll get hydrolysed by sulphuric acid and turn into a carboxylic acid. A & D show that. When treated with H2, all the C=C double bonds will break. That'll make it A.
29. If you draw the compound, you'll see it has no chiral centre. This reaction is nucelophilic addition, not electrophilic. The C-OH step is the last, not the intermediate. That leaves D.
33. A triple bond consists of 2 pi bonds and 1 sigma bond.
38. Draw the compounds you'll get with reactions 1, 2 & 3 and compare them with the compound given.
39. Find the molecular masses of butanone, butanoic acid and 2-methylpropanoic acid. Use the formula actual yield/calculated yield x 100.

 

[h4rriet]

thanks
that was really helpful .. what about my MAIN doubt . i guess u didnt see it no. 10 ?
in q no. 39 ..y cant the oh be dehydrated?

10. 2H2O <-> 2H2 + O2
I = 100(H2) 0(H2) 0(O2)
C = -2x(2H2O) +2x(2H2) +x(O2)
E = 80(2H2O)
x=1o, so the equilibrium concentration of H2=20, and of O2=10.
39. To dehydrate an alcohol, the C of the C-OH has to be attached to a C attached to an H. The C which it is attached to is attached to 4 Carbons and no Hydrogens.

 

[A n g e l a ♥]

and also Q11,24,28,31

 

[h4rriet]

and also Q11,24,28,31

Year/variant what?