Answer:
Option C. 24 days / 4 grams
Explanation:
From the question given above, the following data were obtained:
Days Elapsed >>>> Mass Remaining
0 >>>>>>>>>>>>>>> 16
12 >>>>>>>>>>>>>>> 11
24 >>>>>>>>>>>>>>> 8
36 >>>>>>>>>>>>>>> 6
A. Determination of the half-life of Thorium-234.
To determine the half-life, it is important to know the definition of half life.
Half-life is defined as the time taken for a substance to reduce to half its original mass.
From the table given above, we can see that the original mass of the isotope is 16 g (i.e at 0 day). By day 24, the mass of the isotope is 8 g (i.e half the original mass). Thus, the half-life of the isotope is 24 days.
B. Determination of the mass of the isotope remaining after 2 half lives.
Original amount (N₀) = 16 g
Number of half-lives (n) = 2
Amount remaining (N) =?
N = 1/2ⁿ × N₀
N = 1/2² × 16
N = 1/4 × 16
N = 4 g
Thus, 4 g of the isotope is remaining after 2 half lives.
Summay:
Half-life = 24 days
Amount remaining after 2 half-lives = 4 g
Option C gives the correct answer to the question.
