A generic element, X, is composed of two isotopes, ^40X and ^42X. ^40X has a natural abundance of 75% and an isotopic mass of 39.96 amu, and ^42X has a natural abundance of 25% and an isotopic mass of 41.96 Amy. What is the average atomic mass of this element?

Which of the following is always a reactant in a combustion reaction? oxygen nitrogen hydrogen carbon

Reaction rate depends on how many molecules are coming into contact with each other with enough energy to react. increasing the temperature of the reactants will increase -

Melting and boiling are endothermic processes. this means that these processes absorb energy from their surroundings in order to occur. use this information and the data you collected in the phase change gizmo to describe what happens to the temperature of water when you boil it, then explain why this result occurs.