Answer:
1.) Why does menstruation begin?
A.) Period happens because of changes in hormones in the body.
2.) How long does the menstrual cycle usually last?
A.) the menstrual cycle lasts 21 to 35 days while bleeding between 2 to 7 days
<u>-TheUnknownScientist</u>
Answer:
Human interaction with the ecosystem has rapidly spread disease to Yellowstone's wildlife, which has proven to have adverse effects on populations. Also, humans tend to leave trash in poor areas. Littering is a problem in Yellowstone because it can be ingested by the wildlife and also pollute the park.
Explanation:
Typhoons tend to pass east to west across the Philippine archipelago. Affecting mostly the northern most group of islands (Leyte to Luzon)
Answer
Correct answer is :It has two elements
Explanation
A binary compound is a compound that is made up of two of the elements in the periodic table. Some examples of binary compounds are 
and 
. This means that a binary compound can have more than 2 atoms as in the case of hydrogen oxide. Some binary compounds are ionic as in the case of sodium chloride.This shows that they do not necessarily have to have covalent bonds. This also rules out the possibility that they may always have double bonds as ionic compounds are bound together by ionic bonds. The only thing that will always be true of binary compounds is that they will always have 2 elements.
