DAT Sample test Q70 GC

[babowc]

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Wouldn't the answer be D?
Positron emission = beta-decay, loses an atomic number?

Answer key says E...

 

[HandsOnPractice]

I would definitely put D as well. Not really sure where they got E from, but from my understanding the protons and neutrons on the products and reactants sides must match up and if it was E then they would not. Sorry I couldn't be more help. My guess is the key for that question is wrong. Where did you get the question?

 

[jmh018]

The answer is D. Is this one of the old tests from the ADA? If it is I remember this question but I do not remember the answer being wrong.

 

[babowc]

Yeah, it's the practice that they published on their website.

Thanks guys!

 

[steppingstone]

But wouldn't the answer be E because a positron plus O-8 would give you the correct Nitrogen configuration? If the answer was D, the positron should be placed on the reactants side?

Or am I just reading it wrong? I think E is the right answer...

 

[HandsOnPractice]

I believe you are thinking of B-decay which indeed then we would need O-8 in order to balance the reaction. If we are doing positron emission (which the equation shows) then the daughter nucleus is going to be carbon-13. If we instead chose oxygen-13 to be our daughter nucleus then our parent nucleus would have to be fluorine-13, but since our parent nucleus is nitrogen-13 we know the answer must be "D".

Review Chad's videos on nuclear decay and they will help clear this problem right up!