How many elements are naturally occurring on Earth? too many to count

93

0

118

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.

Use the table to identify the phase and phase changes of the elements under the given conditions. write the name of the substance, phase, or phase change

What type of reaction is shown below? check all that apply. 2h2o2 → 2h2o + o2 synthesis decomposition combustion