The father has to be homozygous for brown eyes(BB) if his children all have brown eyes. Since, the brown eye gene is dominant over blue eyes. All his children will be heterozygous for Brown eyes (Bb).
Carbon binds to oxygen, hydrogen, and nitrogen covalently to form the many molecules important for cellular function. Carbon has four electrons in its outermost shell and can form four bonds. Carbon and hydrogen can form hydrocarbon chains or rings