The answer is Single Replacement.
Pressure what causes the molecules and matter to change .
Activation energy is defined as the least amount of energy that is needed to be available in a chemical system with potential reactants in order to result a chemical reaction. Therefore, the correct answer would be the first option: the heat released in a reaction.
The second level has s and p orbitals, the s orbital holds two electrons and all three p orbitals also hold two each for a total of eight electrons in the second energy level.
