What is the volume of these gases atstp a-3.20x10^-3mol co2

Which of these conditions most likely produces an unstable isotope?

Sally is making a model of a magnesium atom with an atomic mass number of 24 for her chemistry class. she has foam balls for the protons, neutrons, and electrons. she has added 6 neutrons to her model so far. how many more neutrons does she need to add to complete her neutral atom of magnesium?

Explain what happens at the saturation point when adding salt to water at room temperature.