ALL CIE CHEMISTRY DOUBTS HERE !!

[Deadly_king]

Energy at lower temperatures mean we take the graph with the higher peak and not the lower. Thus the answer is C and not D

Yupz........you are right.

I guess I was not very attentive  

Anyway the higher the temperature the more particles will be having activation energy.

The number of particles is represented as the area after activation energy. In this case area is greater for the lower peak.

Hence at lower temperatures, the lower peak should be used.

[Deadly_king]

understood, i thought of that too, but not so sure.Thanks! My friends are sitting for Bio on Thursday too.. I'm not    Good Luck!

Anytime

So you have only one more paper and it's an MCQ.

Thanks

[$!$RatJumper$!$]

W05
12, (I get C. Why D)
15, (I get D)
16,
18,
24, (Why A and not C)
25, (I know it either A or D but cant choose which one)
30, (I dont see how this would be hydrolised)
31,
34,
36, (what does disproportionation mean)
39, (How are hydrocarbons oxidised in a convertor)
40 (What does optically active mean)

Thank you

[Deadly_king]

W05
12, (I get C. Why D)
15, (I get D)
16,
18,
24, (Why A and not C)
25, (I know it either A or D but cant choose which one)
30, (I dont see how this would be hydrolised)
31,
34,
36, (what does disproportionation mean)
39, (How are hydrocarbons oxidised in a convertor)
40 (What does optically active mean)

Thank you

W0w.............all these doubts in only one paper.

Man, you should review your notes again.

Anyway i'll try to help but I might be taking some more time since am pretty busy today. I'll try as hard as possible.

[$!$RatJumper$!$]

W0w.............all these doubts in only one paper.

Man, you should review your notes again.

Anyway i'll try to help but I might be taking some more time since am pretty busy today. I'll try as hard as possible.

Yeah some of us arent as clever as you guys hey
But thankx.. no worries if you're busy...
i got how to do Q16, 25, 30, 31 and 34 .. so no need for those

[Deadly_king]

Yeah some of us arent as clever as you guys hey
But thankx.. no worries if you're busy...
i got how to do Q16, 25, 30, 31 and 34 .. so no need for those

It's not about being clever dude. You're going to have the same exams in 2 days, so you should have been ready.

Nov 05 p1

12. You just need to write the balanced equations for the complete combustion of one mole of each element.

Mg + 1/2O₂ ----> Mg0

Al + 3/4O₂ ----> 1/2Al₂O₃

S + 3/2O₂ ----> SO₃

Hence we can note that the number of moles of oxygen required increases but not constantly from Magnesium to Sulfur.

Answer is D

15. You should first write the balanced equation representing the decomposition of the nitrate. That will be:

Ca(NO₃)₂ -----> CaO + 2NO₂ + 1/2O₂

From equation:
1 mole of nitrate gives 1/2 mole of oxygen gas.
164g of nitrate produces (24/2) dm³ of oxygen gas.
Hence 8.2g of nitrate will emit (12/164 x 8.2) = 0.6dm³ = 600cm³

Answer is C

19. Chiral centres are shown by a carbon atom carrying 4 different group of atoms. No carbon involved in a C=C will be able to show chirality.

Hence this leaves us with only two chiral centres. Starting from the right, they are the second and the third carbon atom

Answer is B

24. I'll proceed by elimination.

Propan-2-ol and 2-methyl-propan-2-ol are first to be rejected since they can form only one type of alkene due to free rotation.

2-methylbutan-2-ol can form only 2 types of alkenes due to free rotation. It is connected to three other carbon atoms and should have been able to form 3 alkenes but two of them are identical.

Butan-2-ol should have formed only two types of alkenes but one of them show cis-trans isomerism. Hence it forms 3 types of alkenes.

Answer is A.

36. A reaction in which the same element is both oxidized and reduced is called a disproportionation reaction.

Is that enough or should I go in more details?

39.

Unburnt hydrocarbons are made to burn completely to form carbon dioxide and water. Hence this is a form of oxidation. Oxygen comes from the oxides of nitrogen which in turn gets reduced.

[$!$RatJumper$!$]

Thankx a ton for the help buddy!
I understood all that you mentioned.. but i think you did no 19 instead of no 18

If you have time please do it, otherwise its fine. Thankx again +rep

[Deadly_king]

Thankx a ton for the help buddy!
I understood all that you mentioned.. but i think you did no 19 instead of no 18

If you have time please do it, otherwise its fine. Thankx again +rep

Anytime

Ooh yeah.......I'm sorry for the confusion.

18. CaO is a basic oxide while ammonium sulfate is some kind of acidic as H⁺ can be liberated from NH⁴⁺. So they'll react together to give off ammonia, which being a gas will rise into the atmosphere. Hence the soil will lose its nitrogen which is required by plants.

Answer is C.

[$!$RatJumper$!$]

Thank You

[Hypernova]

+ rep DK for all of that

[$!$RatJumper$!$]

S06 Q 10, 12, 17, 21, 25

Thank you kindly

[birchy33]

You guys have been terrific and I hate to bundle you with more questions  ... but 
O/N 09 QP1 variant 2

Q20
Q23
Q27

and to my much embarrassment ... Q1: I know its either A or D but I've completely forgot how to pick which one.

Cheers brudas.

[Master_Key]

You guys have been terrific and I hate to bundle you with more questions  ... but 
O/N 09 QP1 variant 2

Q20
Q23
Q27

and to my much embarrassment ... Q1: I know its either A or D but I've completely forgot how to pick which one.

Cheers brudas.

O/N 09 QP1 Variant 2.

Q1. Answer is D.

It is because 0.2 Moles of HC burn to give 35.4 g of CO₂.

So, RFM of CO₂=(12+(16*2)=44 g.

35.4/44 = 0.8

0.8 = 0.2
?    = 1

0.8/0.2=4

This is the simplest method. We get 4 Carbon atoms in one molecule of HC.

Do the Same with Water and we will get 8 Hydrogen atoms.

So the formula is C₄H₈

[Master_Key]

You guys have been terrific and I hate to bundle you with more questions  ... but 
O/N 09 QP1 variant 2

Q20
Q23
Q27

and to my much embarrassment ... Q1: I know its either A or D but I've completely forgot how to pick which one.

Cheers brudas.

O/N 09 QP1 Variant 2.

Q23. Answer is A.

The diagram shows 2 double bonds between C=C atoms. These are the bonds which are broken and Hydrogen or Bromine added. The C=O will not break. Both the double bonds break and form a single bond C-C. 2 Hydrogen atoms are bonded with two Carbon atoms. There are four carbon atoms so 4 Hydrogen atoms.

This gives to 2 moles of both substances as both exist as diatomic molecules.

[elemis]

S06 Q 10, 12, 17, 21, 25

Thank you kindly

Question 17

Chlorine displaces Iodine from the salt. So the Iodide anions lose electrons to chlorine i.e. they are oxidised.