Depends on the instrument.

Flute, Bassoon, Clarinet, Bass Clarinet, Alto Sax, French horn, Euphonium, Tuba--end of the row

Oboe--1st chair sits nearer to clarinets than flutes

Tenor Sax, Bari Sax--1st chair sits nearer to Alto section

Trumpet, Trombone, Bass Trombone--1st chair tends to play first part so in the middle (with the 3rd trumpets closer to the tuba/euphonium; 2nd trumpets closer to saxes/clarinets); bass trombone closer to the tubas