A woman of genotype xhxh mates with a man of genotype xhy. they have a daughter with the abnormal genotype xhxhxh. if nondisjunction occurred in the father, when did it occur and what was the genotype of the abnormal sperm

The maternal genotype is xhxh, so the mother can only contribute xh to the gamete, one way or another.

Therefore the father's contribution is xhxh (=genotype of sperm), which happens to be the result of nondisjunction. Since xhxh is the result of nondisjunction of homologous chromosomes, it occurred in meiosis I.