Answer:
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Explanation: im smart
Answer: The answer is 6.78 grams.
Explanation: The equation used for solving this type of problems is:
where, 
is the initial amount of radioactive substance, N is the remaining amount and n is the number of half lives.
Number of half lives is calculated on dividing the given time by the half life.
n = time/half life
Time is given as 48.0 hours and the half life is given as 4.536 days. let's make the units same and for this let's convert the half life from days to hours.
= 108.864 hours
So, 
= 0.441
Since 5.00 g is the required amount when the radioactive substance is delivered to the scientist, it would be the final amount that is N. We need to calculate the initial amount. Let's plug in the values in the equation:
= 6.78 g
So, 6.78 g of the radioactive substance needs to be ordered.
There should be no air bubbles, as a bubble bursting can affect the volume measurement and disrupt the accuracy of the experiment.
The answer is that both models stated that Earth is the center of the system around which other objects orbit.
That is Aristotle’s model similar to Ptolemy’s model in the way that both stated that Earth is the center of the system around which other objects orbit.
Ptolemy’s model stated that Earth is the center of universe and other the sun, moon, planets, and stars revolving about it in circular orbits at increasing distance.
Aristotle’s model stated that the Sun, the Moon, the planets, and the stars travel in different separate spheres. And music of the spheres can be listen when the spheres touch each other. can be heard. He proved that the Earth is spherical,also stated that it is the the center of the universe.
