Which element has the same number of energy levels as aluminum (Al) and the same number of valence electrons as calcium (Ca)

How has the scientific community addressed the safety of chemicals? a. chemicals are repeatedly tested, even those that have existed for a long time. b. existing chemicals are tested if they have never been tested before. c. chemicals are tested if they are suspected to have caused a problem. d. only new chemicals are tested.

2points what is the job of a scientist? a. to answer ethical questions. b. to write laws based on his or her knowledge. c. to ask and answer scientific questions. d. to ignore facts that do not support his or her theory.

How many moles of carbon dioxide will form if 2.5 moles of c3h8 is burned