In what way are elements in the same column of the periodic table the same?
a) they have the same number of protons.
b) they have the same number of neutrons.
c) they have the same number of electrons.
d) they have the same number of electrons in their valence shell.
e) they have the same number of electron shells.

Organisms are classified, or grouped into categories, based on similarities in their characteristics and/or evolutionary relationships. the study of how organisms are classified is known as

Which of the following is likely not involved in this example of ecological succession? a) the rotting remains of plants add to the fertility of the soil. b)the soil becomes so fertile that eel grass is replaced by other plant species. c) the roots from plants stabilize the sediment, keeping it in place. d) the concentration of salt becomes so high that all plant life is destroyed.

Which chemical reaction shows photosynthesis? a. water + carbon dioxide + sunlight → oxygen + glucose b. carbon + oxygen → carbon dioxide c. hydrogen + oxygen → water d. nitrogen + hydrogen → ammonia