Question

The isotope calcium-41 decays into potassium-41, with a half-life of 1.03 × 105 years. There is a sample of calcium-41 containing 5 × 109 atoms. How many atoms of calcium-41 and potassium-41 will there be after 4.12 × 105 years?

Answer 1

Hey buddy,

● Answer-
Calcium-41 = 3.12×10^8 atoms
Potassium-41 = 4.69×10^9 atoms

● Explaination-
# Given-
Half life = 1.03×10^5 years

# Solution-
- After 1.03×10^5 years (1 half life)
calcium-41 will be 50%
potassium-41 will be 50%
- After 2.06×10^5 years (2 half lives)
calcium-41 will be 25%
potassium-41 will be 75%
- After 3.09×10^5 years (3 half lives)
calcium-41 will be 12.5%
potassium-41 will be 87.5%
- After 4.12×10^5 years (4 half lives)
calcium-41 will be 6.25%
potassium-41 will be 93.75%

After 4.12×10^5 years,
Calcium-41 = 6.25/100 × 5×10^9 = 3.12×10^8 atoms
Potassium-41 = 93.75/100 × 5×10^9 = 4.69×10^9 atoms

Hope this is helpful...

Answer 2

Answer: the person above me is correct

D. 3.125 × 10^8 atoms of calcium-41 and 4.6875 × 10^9 atoms of potassium-41