4) would be your correct answer
Answer: 2 Na (s) + Cl(g) -> 2 NaCl (s)
Explanation:
Phosphorus has 16 neutrons. Phosphorous is 15 on the periodic table, which means that the atomic number (number of protons) of phosphorous is 15.
For more info: https://study.com/academy/answer/what-is-the-number-of-neutrons-in-phosphorus.html
... and a power ot ten.
For example: 1,3x10^21 is in scientific notation, but 13x10^20 is not in scientific notation.
Answer:
C.
increasing level of carbon dioxide