2007 ADA problem #67

[Bobby Fischer]

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"The electronic configuration of a particular neutral atom is 1s2 2s2 2p6 3s2 3p2. What is the number of unpaired electrons in this atom?

A) 1
B) 2
C) 3
D) 4
E) 0"


Seems like a very simple, straightforward question and my answer is 2 unpaired electrons.

Yet the answer key says the answer is 3 (answer C). Huh? Can anyone explain? Boy do I feel like a dummy if this one isn't an error in the answer key

 

[Kingsta2426]

Yes that is an error in the key, you can find the thread that has all of the errors for the 2007 and 2009.

 

[Bobby Fischer]

Yes that is an error in the key, you can find the thread that has all of the errors for the 2007 and 2009.

okay, great feedback and info! Wish I could give you rep points.

I guess the errors* don't exactly inspire confidence in their administration and evaluation of the real thing.👎

*I found another problem where there is an obvious typo

And I thought dentists were detail oriented. Don't let the corporate mindset at Prometric and the ADA know that though or they'd be forced to clean up their act. Whoever let these practice exams go out with errors and omissions are losers.

 

[Kobebucsfan]

they better not have errors on real DAT 😳

 

[Stacker]

"The electronic configuration of a particular neutral atom is 1s2 2s2 2p6 3s2 3p2. What is the number of unpaired electrons in this atom?

A) 1
B) 2
C) 3
D) 4
E) 0"


Seems like a very simple, straightforward question and my answer is 2 unpaired electrons.

Yet the answer key says the answer is 3 (answer C). Huh? Can anyone explain? Boy do I feel like a dummy if this one isn't an error in the answer key

Yeah its wrong and the 4s2 electron only jumps to 3d orbital for Cr or Mo (Cu and Ag).