Which statement accurately describes the relationship between elements and reactivity? A. Elements whose atoms have a filled outer energy level are the most reactive.
B. The most reactive elements are those whose atoms hold tightly onto all of their
electrons.
C. The most reactive elements are those whose atoms can easily lose or gain valence
electrons because they have unfilled valence shells.
D. The most reactive elements are those whose atoms have no valance shell.

c) 50% there are four chromosomes. after crossing over, 2 of the four have been changed. that means any gamete has a 2 in 4 chance or 50% chance of receiving the mutated chromosome.

your answer is going to be physical weathering

the law of original horizontality explains:   why rocks appear in layers. correct answer: b the law suggests that all rock layers are originally laid down (deposited) horizontally and can later be deformed.   the principle is used by geologists to make assumptions about the relative ages of sedimentary rocks.