Tom wanted to test his hypothesis that plants grow better at room temperature than in cold temperatures. he placed an ivy plant in the refrigerator, which had no light source. he also placed a spider plant in the window in his room. what were tom's variables?

Which of the following statements is true? a. elements in the last period are radioactive. b. atomic weight is the same as atomic mass. c. elements in the same group have the same number of electron shells. d. atomic number equals the number of neutrons in the nucleus of an atom.

Based on the equation and the information in the table, what is the enthalpy of the reaction?

Nonpoint source pollution is difficult to control because it