I believe it is the sun, have a good day!
Answer:
Natural selection can cause microevolution (change in allele frequencies).
Explanation:
With fitness-increasing alleles becoming more common in the population.
Three factors that determine the reactivity of elements are the
valence electrons are the electrons in the outermost electron shell of an atom.
The number of electrons in an atom's outermost valence shell governs its
bonding behaviour. That is why in periodic table the elements were put together
according to their numbers of valence electrons.
METALS
The most reactive kind of metallic element is a metal from
Group 1 sodium or potassium.
An atom in Group 1 has only one valence electron.
NON-METALS
A nonmetal tends to attract another valence electrons to
attain a full valence shell.
Cerebellum smoothes and coordinates the movement of skeletal muscle.
