C. Organize it into charts, graphs, do calculation if necessary.
Answer: D) Pulmonary and aortic valves.
Explanation
There are two main heartbeats from a healthy heart.
The first beat is called the S1 or the lub, and it occurs when the atrioventricular valves (comprising the mitral and tricuspid valves) close.
The second beat is called the S2 or the dub, and it occurs when the semilunar valves (comprising the aortic and pulmonary valves) close.
Listening for heart beats is an essential part of cardiac auscultation.
Atoms. Every element is made of a specific type of atoms.
Answer:
The correct option is B. Activation energy
Explanation:
The activation energy is usually used to designate the minimum energy necessary for a given chemical reaction to occur, that is, the basic requirement for the reaction to proceed.
For a reaction to occur between two molecules, they must collide in the correct orientation and have a minimum amount of energy. As the molecules approach, their electron clouds are rejected. This requires energy (activation energy) and comes from the heat of the system, that, is, from translational, vibrational energy, etc of each molecule. If the energy is sufficient, the repulsion is overcome and the molecules are close enough for a rearrangement of the bonds of the molecules.
The concept of Activation energy was introduced by Arrhenius in 1889. Arrhenius suggested that molecules must prossess a minimum amount of energy to react. That energy comes from the kinetic energy of the clliding molecules. Kinetic energy serves to cause reactions, but if the molecules move very slowly, the molecules will only bounce when they collide with other molecules and the reaction does not happen. In order for the molecules to react, they must have a total kinetic energy that is equal to or greater than a certain minimum value of energy called activation energy.
