Calculate the energy, in joules, required to ionize a hydrogen atom when its electron is initially in the n =2 energy level. the energy needed to ionize a ground-state hydrogen atom is 2.18 x 10–18 j.

Compare and contrast physical changes with chemical changes.

How have the greenhouse gasses increased from the year 2000 to 2018

Aglow stick contains a glass vial with chemicals. when the glow stick is bent, the vial breaks and the chemicals react to produce a glow. a science student observes that a glow stick kept in the freezer glows for a longer duration than a glow stick kept at room temperature. what conclusion can be drawn based on the observation? be sure to note the outcome and test variables in the conclusion.