In Grade 5 Music Theory (ABRSM) you have the choice between writing for voice or for instrument.
When writing for instrument, it’s range, characteristics and in some instances different methods of sound production will need to be considered.
For voice, both the range and vocal setting, (i.e. how well you fit the words to music) will also need to be considered.
In this post I’m outlining for reference the 6 instrument types you will need to know the ranges of.