The valence electrons of an atom of which element would feel a smaller effective nuclear charge than the valence electrons of a calcium (ca) atom? a. magnesium (mg) b. potassium (k) c. scandium (sc) d. strontium (sr)

Ants live on acacia trees in south america. the ants feed on sugars secreted by the trees. the trees provide room for the ants to live. the ants sting any other insect or animal that comes to eat the trees. what type of relationship is this?