:)help me plsss

Explanation:

1. The materials are physically combined because all of the materials including the sand, salt, and iron fillings are their own substances and they maintain their original form. This is a mixture and they aren't chemically combined.

2. To separate each of the materials physical means would be used because since they're their own individual substances and have kept their original form they're mixed and not chemically combined.

3. The iron and oxygen atoms in rust are chemically combined because they are no longer individual substances and haven't kept their original form, so therefore they're a chemical combination.

the corpus luteum secretes estrogens and progesterone. the latter hormone causes changes in the uterus that make it more suitable for implantation of the fertilized ovum and the nourishment of the embryo. if the egg is not fertilized, the corpus luteum becomes inactive after 10–14 days, and menstruation occurs.

i hope this : )