From day 15-28 if no fertilization occurs

MENSURATION AND MENSTRUAL CYCLE IS START AND THICK LINING OF UTERUS IS BREAKING AND MENSURATION OCCURS

Since electrons cannot have the same set of quantum numbers, a maximum of two can be in the n = 1 level, and a third electron must reside in the higher-energy n = 2 level. If there are two electrons in the n = 1 level, their spins must be in opposite directions.