Thallium-208 has a half-life of 3 minutes. How long will it take 60.0 g of thallium-208 to decay so that 15.0 g of the thallium-208 remains?
O3 min
O 6 min
O 9 min
O 11min Please explain how you got the answer?

The decay takes 6min

Explanation:

The decay of an isotope as Thallium-208 follows the equation:

ln[A] = -kt + ln[A]₀

Where [A] is amount of isotope after time t

k is decay constant = ln 2 / t(1/2)

[A]₀ is initial amount of the isotope

Replacing:

[A] = 15.0g

k = ln 2 / t(1/2) = ln 2 / 3min = 0.23105 min⁻¹

t = ?

[A]₀ = 60.0g

ln[A] = -kt + ln[A]₀

ln[15.0g] = -0.23105 min⁻¹*t + ln[60.0g]

-1.38629 = -0.23105 min⁻¹*t

6min = t

The decay takes 6min

That result from subduction of oceanic plates beneath lighter continental plates. most of the earth's volcanoes are located around the pacific ring of fire because that the location of most of the earth's subduction zones.

the catch is that the top numbers are atomic masses the bottom numbers are the numbers of protons and electrons in an uncharged atom. they are the number of that atoms as you would find them on the periodic table. further, the numbers on the left are used to determine the missing numbers on the right

so here we go

atomic mass

239 + 1 = y + 134 + 3 combine like terms

240 = y + 137             subtract 137 from both terms

240 - 137 = y

103 = y

atomic number

94 = z +54 + 0

94 = z + 54               subtract 54 from both sides.

40 = z

answer