Author Topic: Urgent As Chemistry Questions!!!  (Read 1477 times)

Offline mousa

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Urgent As Chemistry Questions!!!
« on: November 26, 2009, 08:20:56 am »
those are for cie As chemistry paper one...

Q2 june 2006

Q5 nov 2004

Q2 june 2003

your help will be much appreciated :)

Offline MaNi_DaDuDe

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Re: Urgent As Chemistry Questions!!!
« Reply #1 on: November 26, 2009, 01:17:10 pm »
those are for cie As chemistry paper one...

Q2 june 2006

Q5 nov 2004

Q2 june 2003

your help will be much appreciated :)

- 2 A sample of chlorine containing isotopes of mass numbers 35 and 37 was analysed in a
mass-spectrometer.
How many peaks corresponding to +2 Cl were recorded?
A 2 B 3 C 4 D 5

B - is the answer. I have no clue why.

5 An atom has eight electrons.
Which diagram shows the electronic configuration of this atom in its lowest energy state?

B - is the answer. Well that's how you would put the electrons in the shells - that's the sequence. Plus, the paired electron in the p sub-shell makes it unstable; thus the energy needed to remove it is less as there is repulsion by the other electron in the subshell. (I think - I would have put B, anyway.)

How many moles of hydrogen are required to convert one mole of glyceryl trieleostearate into the
soft margarine?
A 4 B 5 C 6 D 9

The answer is B - I am not sure. I think you make a balanced equation and that's how you get it.


Sorry I wasn't much of help; I'm just a little hungry and confused right now. :(

pz

Offline 123

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Re: Urgent As Chemistry Questions!!!
« Reply #2 on: November 26, 2009, 03:40:52 pm »
..........
How many moles of hydrogen are required to convert one mole of glyceryl trieleostearate into the
soft margarine?
A 4 B 5 C 6 D 9

The answer is B - I am not sure. I think you make a balanced equation and that's how you get it.


Sorry I wasn't much of help; I'm just a little hungry and confused right now. :(
pz
Lol.."hungry"!  :D
About the question... just count up the H atoms in the given formula. And count the H atoms in the formulas which they said goes in 1 chain & the other one thats in 2chains.Find difference of no. of H atoms. That should give 5 moles of H atoms. I guess in hydrogenation H2 is used but thats in H molecules. They have just said moles of Hydrogen....so assume that its in atoms..


Offline mousa

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Re: Urgent As Chemistry Questions!!!
« Reply #3 on: November 26, 2009, 05:22:45 pm »
Thanks alot guys...any more responses?? ::)

Offline MaNi_DaDuDe

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Re: Urgent As Chemistry Questions!!!
« Reply #4 on: November 26, 2009, 10:12:07 pm »
Lol.."hungry"!  :D
About the question... just count up the H atoms in the given formula. And count the H atoms in the formulas which they said goes in 1 chain & the other one thats in 2chains.Find difference of no. of H atoms. That should give 5 moles of H atoms. I guess in hydrogenation H2 is used but thats in H molecules. They have just said moles of Hydrogen....so assume that its in atoms..



Yeah I was fasting.. :(

Offline Light

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Re: Urgent As Chemistry Questions!!!
« Reply #5 on: November 27, 2009, 12:49:21 am »
the first ques: Cl2 can be made into 3 fragments :35Cl35CL,35Cl37Cl,37Cl37Cl.
2nd ques:u have to follow pauli exclusion rule and hunds rule.the electrons has be filled singly first in one direction and in increasing energy level..A and C is out due to the double pair but there still empty orbital.it cannot happen as the second electron can pair only when the orbital  is occupied singly.D is the excited state (perhaps of hybridisation)so high energy level.B is correct ans.
 3rd ques not need equation.u compare the  double bonds of reactants and product.1 double bond require 1 mol of H2.U will see 5 double bond undergoes hydrogenation.so 5 mol of H2.

Offline mousa

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Re: Urgent As Chemistry Questions!!!
« Reply #6 on: November 27, 2009, 02:21:36 am »
the first ques: Cl2 can be made into 3 fragments :35Cl35CL,35Cl37Cl,37Cl37Cl.
2nd ques:u have to follow pauli exclusion rule and hunds rule.the electrons has be filled singly first in one direction and in increasing energy level..A and C is out due to the double pair but there still empty orbital.it cannot happen as the second electron can pair only when the orbital  is occupied singly.D is the excited state (perhaps of hybridisation)so high energy level.B is correct ans.
 3rd ques not need equation.u compare the  double bonds of reactants and product.1 double bond require 1 mol of H2.U will see 5 double bond undergoes hydrogenation.so 5 mol of H2.

Thanks alot lighty..