Which of the following events separate geologic time into eras and periods...
the appearance and disappearance of volcanoes
the appearance and disappearance of groups of organisms
the creation of new ocean ridges
the number of earthquakes occurring at that time
Hey! Your answer would be the appearance and disappearance of group of organisms . Hope this helps!
The geological time scale refers to the sequential arrangement of all the major and minor events that have taken place in the past. This scale is divided into some major eons and eras and some subdivisions such as period and age.
The eras and periods are primarily marked by the appearance and disappearance of a group of organisms that allowed the geological time to be separated. There are three main eras namely the Paleozoic, the Mesozoic, and the Cenozoic.
The Paleozoic era was marked by the presence of simple organisms and index fossils both in the terrestrial as well as in the marine ecosystem, such as trilobites, fishes, reptiles, brachiopods, bivalves, and gastropods.
The Mesozoic era was marked by the presence of dinosaurs that ruled the earth's surface some 150 million years back. They were dominantly present and scattered in almost all parts of the land.
The Cenozoic era is the third one that is marked by the appearance, evolution, and presence of various groups of organisms such as horses, mammals, and humans.
Thus, the correct answer is option (2).
for a exothermic reaction, the energy is released i.e. the energy of the products is lower than the energy of the reactants.
= energy of products
= energy of reactants
as , thus comes out to be negative. negative value of enthalpy shows that the reaction is exothermic.
the electron configuration that you gave me has 16 electrons ergo it has 16 protons ergo it is the element sulfur.