To solve this problem we can apply the concept related to thermal expansion, including the analogy with resistance and final intensity.
The mathematical expression that describes the expansion of a material by a thermal process is given by

Where
= Initial resistance
Thermal expansion coefficient
Change in the temperature
If we want to directly obtain the final value of the resistance of the object, you would simply add the initial resistance to this equation - because at this moment we have the result of how much resistance changed, but not of its final resistance - So,


Re-arrange to find the change at the temperature,

Since the resistance is inversely proportional to the current and considering that the voltage is constant then

Then,




<em>(It is possible that there is a typing error and the value is not 4.5 but 4.3, so the closest approximate result would be 1627K and mark this as the correct answer)</em>
After one half-life, 8 g of radioactive isotope will remain in the sample.
<h3>What is radioactivity?</h3>
The act of producing radiation spontaneously is known as radioactivity. This is accomplished by an unstable atomic nucleus that want to give up some energy in order to move to a more stable form.
The following formula is used to compute the number of half lives elapsed:

Hence,8 gram of radioactive isotope remains in the sample after 1 half-life.
To learn more about the radioactivity, refer to the link;
brainly.com/question/1770619
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Photoelectric effect is the emission of electrons by a substance that has been subjected to electromagnetic energy