Which element has 7 valence electrons

Which of the following describes something an engineer would probably do first when developing new technology meant to reduce ocean pollution? o a. evaluate the benefits and challenges of using certain chemicals to purify water. o b. research new scientific findings in regard to ocean cleanup. o c. identify the need to reduce ocean pollution. o d. research what has been done in the past to clean up oceanic oil residue.

Which compound is held together by the electrostatic force between two ions? a. co2 b. cci4 c. h2s d. mgf2

Glass has a hardness that is in the middle of the hardness scale. what is the hardness of glass?