Question

What is the number of nitrogen-based electrons in a `4.2*g` mass of nitride anion?

`A.` `0.30xxN_A;`
`B.` `30xxN_A;`
`C.` `3.0xxN_A;`
`D.` `4.2xxN_A;`
`E.` `"cannot be determined..."`

Answer 1

Well, nitrogen has `Z=7`............

Explanation:

And if `Z=7`, and we have `N^(3-)`, we have 10 electrons per atom, i.e. `10*e^(-)xxN_A` electrons per mole of nitride anion.

But we have a mass of `4.2*g`, which corresponds to a molar quantity of `(4.2*g)/(14.01*g*mol^-1)=0.30*mol`.

And thus in a `0.30*mol` quantity of nitride anion, there are `10xx0.30*molxxN_A` quantity of electrons........ So we choose `"option c"`.

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