An astronaut in the international space station cannot stand on a weighing scale. but an astronaut inside a rotating space station (not yet built) can stand on a weighing scale. explain. your answer

The astronaut when positioned on a scale of an international space station that is static in rotational motion, and turning around the earth, will have no effect, since there is no external force acting on it. This is in perpetual free fall around the earth.

When an astronaut stands on a scale within a rotating space station, he will have the Rotational Centripetal Force acting on it, said Force, from the inside acting as 'Artificial Gravity' which will generate a given measurement on the scale.

.) the observation by semmelweis that more mothers died of childbed fever when their doctors also worked in the morgue

the answer would most likely be c, because if it's a comical piece of information, it may likely not be true, if it's a site that allows anybody to edit the content, it could mean a five year old is typing the info, and if it's a tv show produced by a celeb, it may have a biased opinion.