Mathematics: Sodium-24 has a half-life of 15 hours.how many grams of a 900 g sample will remain after 90 hours? a) 7.03125 gb) 7.5 gc) 14.0625 gd) 28.125 g

3201step-by-step explanation:...

Sodium-24 has a half-life of 15 hours.how many grams

amarionlucas06

05.06.2020

The amount left after 90 hours is 14.0625 g

Step-by-step explanation:

This is the case of an exponential decay of Sodium-24. The function for exponential decay is,

y(t)=a(1-r)^n

where,

y(t) = amount left after time t

a = initial amount = 900 g

r = rate of decay = 0.5 (as the sample is getting halved each time)

t = number of periods = $\dfrac{90}{15}=6$ (as we have to convert the period in terms of half lives)

Putting the values,

y(t)=900(1-0.5)^6

=900(0.5)^6

$=14.0625\ g$

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