Answer: Chemical composition modification (or, physical signal would be color).
As the O3 suggests, the Ozone molecule is made up of 3 Oxygen atoms.
Answer:
2.74 x 1023 molecules of CO2.
Explanation:
There are 2.74 x 1023 molecules of CO2.
There are 30 protons and 39 neutrons in the nucleus.
This must me the isotope of an element with an atomic mass close to 69 u.
The only candidates are Zn and Ga.
Zn has a zinc-69 isotope with mass 68.926 u.
Ga has a gallium -69 isotope with mass 68.925 u.
The isotope is probably

.
It has 30 protons and 39 neutrons.
D. Kinda simple, don’t think much explaining is needed.