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Chemistry: Post your doubts here!

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haha man im screwed ! look all i know is am applyin for edexcel
nd some of my frndz did it in jan so thts what i was askin for !
I understand. The correct sub-forum for you is this, which deals with discussion of Edexcel papers, etc: http://www.xtremepapers.com/community/forums/edexcel.17/
You can get advanced level chemistry papers from here: http://www.xtremepapers.com/Edexcel/index.php?dir=Advanced Level/Chemistry/
But the Jan 2012 is not available yet. :/
 
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Plz solve this mcq:
A sample of chlorine containing isotopes of mass numbers 35 and 37 was analysed in a
mass-spectrometer.
How many peaks corresponding to
Cl2(charge on CL +1) were recorded?
A 2 B 3 C 4 D 5
C is the answer
The possible peaks are:
Cl-35 Cl-35
Cl-35 Cl-37
Cl-37 Cl-35
Cl-37 Cl-37
 
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Use of the Data Booklet is relevant to this question.
What mass of solid residue can be obtained from the thermal decomposition of 4.10 g of
anhydrous calcium nitrate?
A 0.70g B 1.00g C 1.40g D 2.25g
C is the answer
Construct the equation:
Ca(NO3)2 -----> CaO + 2NO2 + (1/2)O2
solid residue is CaO
Mr is 164 and 56 respectively
So
Ca(NO3)2 : CaO
164 : 56
4.10 : x
By calculation,
x = (56*4.10)/164
x = 1.40
:)
 
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C is the answer
The possible peaks are:
Cl-35 Cl-35
Cl-35 Cl-37
Cl-37 Cl-35
Cl-37 Cl-37
Is it C? I think Cl-35 Cl-37 and Cl-37 Cl-35 shall show as the same peak. The mass spectrometre measures the mass-to-charge ratio of Cl2 molecules, not Cl atoms.
 
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1,594
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483
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93
Plz solve this mcq:
A sample of chlorine containing isotopes of mass numbers 35 and 37 was analysed in a
mass-spectrometer.
How many peaks corresponding to
Cl2(charge on CL +1) were recorded?
A 2 B 3 C 4 D 5
AoA!
B. 3 peaks will be recorded corresponding to Cl2 (1+). Chlorine atoms can exist in the form of Cl-35 and Cl-37. So the three peaks will correspond to the following three possibilities of Cl2 (1+):
-> Cl-35 and Cl-37
-> Cl-35 and Cl-35
-> Cl 37 and Cl-37
 
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Is it C? I think Cl-35 Cl-37 and Cl-37 Cl-35 shall show as the same peak. The mass spectrometre measures the mass-to-charge ratio of Cl2 molecules, not Cl atoms.
i agree....the answer shud b "B".......
 
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AoA!
B. 3 peaks will be recorded corresponding to Cl2 (1+). Chlorine atoms can exist in the form of Cl-35 and Cl-37. So the three peaks will correspond to the following three possibilities of Cl2 (1+):
-> Cl-35 and Cl-37
-> Cl-35 and Cl-35
-> Cl 37 and Cl-37
exactly........
 
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