Which of the following celestial body is a newly developed star who's core has not begun nuclear fusion reactions? (Also means "New Star")

A- nebula
B-sun
C-frodostar
D-protostar

Which statement best describes the oxidation numbers of the atoms found in magnesium chloride? a. magnesium has a 2- oxidation number and chlorine has a 1+ oxidation number. b. magnesium has a 2- oxidation number and chlorine has a 2+ oxidation number. c. magnesium has a 2+ oxidation number and chlorine has a 1- oxidation number. d. magnesium has a 1+ oxidation number and chlorine has a 1- oxidation number.

Describe at least two advantages and two disadvantages of using hydropower as a source of energy.

Who discovered a pattern to the elements in 1869?