From which region in the Middle East are modern Arabs descendants of?

Which process collects sample soils from particular areas of a site? a.) repetitive sampling b.) restorative sampling c.) random sampling d.) representative sampling

Which of the following is not a challenge to instituting sound global environmental policies? a. most changes are inexpensive and easy to implement. b. elected leaders who support unpopular environmental issues often are not re-elected. c. economic considerations outweigh environmental ones in many societies. d. there is no way to enforce international environmental agreements.

What does 2[tex] {2}^{ - 4} \times {2}^{ - 2} [/tex]