Elements that have the same number of protons but a different number of neutrons in the nucleus are called A periods.
B metalloids.
C groups.
D isotopes.​

Skulls of (1) modern gorilla, (2) australopithecus afarensis, (3) homo erectus, (4) homo neanderthalensis, (5) homo sapiens based on the diagram, which of the following best describes ways in which the physical appearance of h. neandertalensis and h. sapiens differ? (2 points)

Of the pollutants that form acids in the atmosphere, which is easiest to reduce? a. sulfur dioxide b. nitrogen dioxide c. ozone d. carbon monoxide

Which of the following is one of the four conditions necessary for natural selection to occur in a population? fewer organisms are born than the habitat can support mutation does not occur organisms have identical characteristics variation is inherited