pinyin: fēn; fèn

Chinese phrase: 分开 fēn kāi - to divide, separate
分数 fēn shù - point, marks etc. gotten in exams, matches etc.
成分 chéng fèn - elment

Examples:
芬
pinyin: fēn;
Chinese phrase: 芬芳 fēn fāng
- fragrant

粉
pinyin: fěn;
Chinese phrase: 药粉 yào fěn - medical powder
粉碎 fěn suì - to break into pieces; cause sth. to be powder

份
pinyin: fèn;
Chinese phrase: 一份 yī fèn - a share, part, portion