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?

here

Explanation:

4.12× 105 years means that those atoms have passed 4 half lives.

In the first half life,

In the second half life,

In the third half life,

In the fourth half life, the remaining Ca-41 atoms will be,

So after 4 half lives, the remaining Ca-41 atoms are 3.125×108. The amount of formed K-41 atoms will be,

d

explanation:

v=uf/(u-f)

= 5.10/(5-10) convex lens has positive focal length

=50/-5

=-10 cm (formed at other side)