A purple liquid is heated with fire. Eventually, it starts to boil. A white gas appears, leaving behind a purple salt-like solid. What type of matter is the purple liquid? Explain your answer.

since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.

1.solid

2.carbon dioxide

3.helium