[fetusinprogress]

here is a 2 ethylpentane...where do I attach the
nitrile

[sjb]

As it isn't mentioned, I'd put it at the 1 position, but be careful not to add an extra carbon-triple bond nitrogen there, as the carbon is already in place.

It may be easier if you start with pentanenitrile, then add an ethyl to the 2-position. It should make no difference in this case. Seehttp://www.chem.uic.edu/web1/OCOL-II/WIN/CH21/F1.HTM

Are you happy assigning priorities and hence drawing the (R) form?

[AWK]

here is a 2 ethylpentane...where do I attach the
nitrile

2-ethylpentane is a nonsense name