Would the reaction of cesium, Cs, with oxygen be more or less vigorous than K?

So the ionization energy in K is less than that in Na or in Li. So Potassium is more reactive than many other metals. However, Rubidium Rb and Cesium Cs are more reactive than Potassium. ... However they are bigger than Potassium and so are more ready than K to lose electrons

1.solid

2.carbon dioxide

3.helium