The event in the life of a star that begins its expansion into a giant is its core that was hot enough for fusion reaction.
<h3>What is fusion reaction?</h3>
Nuclear fusion is a type of reaction in which two or more atomic nuclei are fuse to form one or more different atomic nuclei with the release or the absorption of energy.
So we can conclude that the event in the life of a star that begins its expansion into a giant is its core that was hot enough for fusion reaction.
Learn more about reaction here: brainly.com/question/26018275
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Taking into account the rule of three for the change of units, the mass of the book is 45600 miligrams.
First of all, the rule of three is a mathematical tool that helps you quickly solve proportionality problems.
Having three known values and one unknown, a proportional relationship is established between all of them in order to find the fourth term of the proportion.
If the relationship between the magnitudes is direct (when one magnitude increases, so does the other; or when one magnitude decreases, so does the other), the rule of three is applied as follows, where a, b and c are known values and x is the unknown to calculate:
a → b
c → x
So: 
Being 1 kg equivalent to 1000000 milligrams, In this case the rule of three is applied as follows: if 1 kg equals 1000000 milligrams, 4.56×10⁻² kg equals how many milligrams?
1 kg → 1000000 milligrams
4.56×10⁻² kg → x
So:

<u><em>x=45600 miligrams</em></u>
In summary, the mass of the book is 45600 miligrams.
Learn more:
Thermal energy is converted to radiative energy via molecular collisions and released as photons.
C. meter per second
Velocity and speed share the same SI unit.
They’re falling toward earth & moving forward at about the same velocity. because the downward and forward forces are nearly equal, the astronauts are not pulled in any specific direction, so they float . <span>
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