Atomic physics is the field of physics that <span>studies atoms.
</span>In 1913, Niels Bohr made a theory for the hydrogen atom based on quantum theory which states<span> that energy can only be transferred in certain quantities. Electrons move around the nucleus but only in fixed orbits. When an atom jumps from one orbit to another with lower energy level, a light quantum is emitted as a result.</span>
Answer:- 0.143 M
Solution:- HCl and NaOH reacts in 1:1 mol ratio as shown in the below reaction:

Let's calculate the initial moles of HCl and the moles of NaOH added to it:

= 0.075 mol HCl

= 0.025 mol NaOH
Since they react in 1:1 mol ratio, 0.025 mol of NaOH will react with 0.025 moles of HCl.
Remaining moles of HCl = 0.075 - 0.025 = 0.050
Total volume of the solution = 0.250 L + 0.100 L = 0.350 L
So, the concentration of HCl in the resulting solution = 
= 0.143 M
Hence, the concentration of HCl acid in the resulting solution is 0.143 M.
During endothermic phase change, the potential energy of the system always increases while the kinetic energy of the system remains constant. The potential energy of the reaction increases because energy is been added to the system from the external environment.
<u>Explanation</u>:
- Those are three distinct methods for demonstrating a specific energy condition of an object. They don't affect one another.
- "Potential Energy" is a relative term showing a release of possible energy to the environment. If we accept its pattern as the overall energy state of a compound, at that point, an endothermic phase change would infer an increase in "potential" as energy is being added to the compound by the system.
- A phase change will display an increase in the kinetic energy at whatever point the compound is transforming from a high density to a low dense phase. The kinetic energy will decrease at whatever point the compound is transforming from a less dense to high dense phase.