The 3d sublevel is not filled until after the 4s sublevel, because the 3d sublevel has more energy than the 4s sublevel, and less energy than the 4p sublevel. (:
A star’s spectrum will change over time due to it being dependent on some properties in the photosphere such as :
<h3>What is a Star?</h3>
This refers to an astronomical object composed of hydrogen and helium and held together by gravity. As stars age or get older, changes occur but are very slow.
This is why most stars spend their lifetime in the main sequence but does't invalidate that they won't remain constant as their constituents also become used up with time.
This is therefore the reason why star’s spectrum will change over time as the most appropriate choice.
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The color changes to a blue green color because of the acidity/pH in water. Example is the statue of liberty
<h3>Answer:</h3><h2>Similarities</h2>
- Fresh water and marine water both are essential parts of the water cycle.
- They contain the same chemical and the amount of minerals in both the ecosystems is same.
- Both addresses to the aquatic development.
<h2>Dissimilarities</h2>
- Marine water carries much higher amounts of suspended chemicals as related to fresh water.
- This larger collection of the chemical also increases the quantity of salt in marine water than that of fresh water.
- Plant and animals existing in these water bodies also differ.