Chemistry MCQ thread...

[Zishi]

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

Are you pretty sure that what you've posted is correct? Tell me from which year is this? Also tell the question number. I'll answer it after seeing the original question...

 

[Hateexams93]

yeah..and its Cl 2+ (not +2Cl), its may june 2006 http://www.xtremepapers.me/CIE/Internat ... 6_qp_1.pdf
Q2

 

[Zishi]

yeah..and its Cl 2+ (not +2Cl), its may june 2006 http://www.xtremepapers.me/CIE/Internat ... 6_qp_1.pdf
Q2

Your wording was misleading. It's actually Cl_2 ^+ . As it contains two Cl atoms so they can be arranged like this:

Cl-35 + Cl-35 = Cl_2
Cl-35 + Cl-37 = Cl_2
Cl-37 + Cl-37 = Cl_2

So there must be three peaks.

 

[hassam]

GOOD question to test ur concepts on boltzmann distribution

 

[Hateexams93]

Cl-35 + Cl-75 = Cl_2
where did u get Cl-75 from ?

 

[Zishi]

GOOD question to test ur concepts on boltzmann distribution

My answer is B. What does the mark scheme say?

Cl-35 + Cl-75 = Cl_2
where did u get Cl-75 from ?

Sorry, it was a typo. It is 37 instead of 75.

 

[xHazeMx]

Cl-35 + Cl-75 = Cl_2
where did u get Cl-75 from ?

he means chlorine exists in 2 forms 35.5 and 37 .. chlorine molecule contains 2 atoms as it is diatomic gas so,

35.5 + 37
35.5 + 35.5
37 + 37
these would give u three different peaks

 

[hassam]

GOOD question to test ur concepts on boltzmann distribution

My answer is B. What does the mark scheme say?

u r ryt...k ready for next one,.....

 

[xHazeMx]

GOOD question to test ur concepts on boltzmann distribution

its B right ?

 

[Zishi]

Cl-35 + Cl-75 = Cl_2
where did u get Cl-75 from ?

he means chlorine exists in 2 forms 35.5 and 37 .. chlorine molecule contains 2 atoms as it is diatomic gas so,

35.5 + 37
35.5 + 35.5
37 + 37
these would give u three different peaks

LOL! No these won't give three different peaks.

These would give:
Cl-35 + Cl-35 = Cl_2
Cl-35 + Cl-37 = Cl_2
Cl-37 + Cl-37 = Cl_2

35.5 is the Ar - not the isotopic mass.

 

[Zishi]

GOOD question to test ur concepts on boltzmann distribution

My answer is B. What does the mark scheme say?

u r ryt...k ready for next one,.....

I'm ready! Hassam rocks!! From which exam board do you get these questions btw?

 

[xHazeMx]

because i didn't see the question

 

[Hateexams93]

Zishi can u explain the concept of the mass spectrometer , i always get confused while solving these kind of questions

 

[Zishi]

Zishi can u explain the concept of the mass spectrometer , i always get confused while solving these kind of questions

What do you exactly want to know about it? On what things do you get stuck?

 

[hassam]

 

[Hateexams93]

peaks ,what do they indicate ??i thought they r showing the number of isotopes*

 

[Hateexams93]

Hassam is it 1 ??

 

[hassam]

no...let zishi anser

 

[xHazeMx]

its B ( 1 and 2 ) right?

 

[Zishi]

I'd say that B is its answer. That is only options number 1 and 2 are correct. But I may be completely wrong. :roll: