נבחר
נבחרת, נבחרים, נבחרות

Ha-nivkhar- heh nun bet khet reish -sing. masc. (ha - the, I don't know if you need it, as you have provided no context)

nivkheret -nun bet khet reish tav - sing. femin.
nivkharim - nun bet khet reish iud mem - pl. masc.
nivkharot - nun bet khet reish vav tav - pl. femin.

But if you need a Biblical phrase "chosen people", then it is
עם הבחירה
am - ain mem - people
ha-bkhira - the choice

נבחר
nivchar (male)
נבחרת
nivcheret (female)