Both. Electrons absorb energy and move to a higher energy state, which is unstable, and they fall back down to their ground state immediately, releasing energy as they do.
Assuming the M is molarity, molarity is equal to mols/volume in liters.
So it would be 50M NaCl = X mols/ 1.0L
50M * 1.0L = X mols
X = 50
50 Mols of NaCl
Now that you have mols, you can then convert mols to grams by doing 50mols NaCl * (58.44 g NaCl/ 1 mol NaCl)
= 2922 grams of NaCl
The amount of chemical energy a substance has is influenced by its structure and the bond the substance has.
Some bond is release energy when broken, other bond need some energy to break. The structure will also influence the chemical energy.
One of substance with high chemical energy is adenosine triphosphate which was used as energy source in a living organism. The phosphate bond in this molecule worth about 30.5 kJ/moles
Solar energy will not run out (unless the sun burns out), but the supply of fossil fuels we use is slowly depleting. Burning fossil fuel also releases greenhouse gas into the air, which is bad for the atmosphere.
Your body changes your body and it deadges.
