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Author Topic: Test Question: Moles of nuetrons  (Read 573 times)

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serendipityfox

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Test Question: Moles of nuetrons
« on: December 29, 2016, 06:39:39 PM »

Hello i am working though basic pre grad test questions and this one came up which has me completely stymied:

which one of the following has one mole of nuetrons:
a) 1g of 1/1 H
b) 1g of 12/6 C
c) 2g of 24/12 Mg
d) 2g of 22/10 Ne

Please explain why..
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AWK

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serendipityfox

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Re: Test Question: Moles of nuetrons
« Reply #2 on: December 29, 2016, 09:19:43 PM »

can't seem to get the super and subscript on the same symbol!
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AWK

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Re: Test Question: Moles of nuetrons
« Reply #3 on: December 29, 2016, 09:40:43 PM »

Quote
22/10 Ne
All is written in one line(superscript/subscript element name) and "10" is actually superfluous (10 means Ne).
Treat such symbols as 22Ne, 12C and so on
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Vidya

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Re: Test Question: Moles of nuetrons
« Reply #4 on: January 01, 2017, 11:36:37 PM »

Hello i am working though basic pre grad test questions and this one came up which has me completely stymied:

which one of the following has one mole of nuetrons:
a) 1g of 1/1 H
b) 1g of 12/6 C
c) 2g of 24/12 Mg
d) 2g of 22/10 Ne

Please explain why..
If mass is given then you need to convert mass into moles.Do you know how to go from mass to moles ?Can you calculate number of moles in each part?

Enthalpy

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Re: Test Question: Moles of nuetrons
« Reply #5 on: January 02, 2017, 03:36:20 AM »

which one of the following has one mole of nuetrons:
a) 1g of 1/1 H
b) 1g of 12/6 C
c) 2g of 24/12 Mg
d) 2g of 22/10 Ne
There are fewer moles of a heavier element in a gram, but a mole of a heavier element contains more neutrons.

Or a simpler approach: how much does a mole of neutrons weigh?
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sjb

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Re: Test Question: Moles of nuetrons
« Reply #6 on: January 02, 2017, 05:59:53 AM »

Or a simpler approach: how much does a mole of neutrons weigh?

I'm not sure this is a correct approach, given binding energy considerations. Perhaps Vidya's approach is better?
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Enthalpy

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Re: Test Question: Moles of nuetrons
« Reply #7 on: January 04, 2017, 04:08:41 AM »

The simple figures in the question (1g, 2g, 12/6) tell that the binding energy shall be neglected. If you compute the binding energy in, you'll find no correct answer among the proposed ones, which are integers.
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