Question

If you have 100 grams of a chemical with a half-life of 8 days, then how much will you have after 40 days?

A. 6.25

B. 20 g

C. 12.5 g

D. 3.125 g

Answer 1

Answer:

option d = 3.125 g

Explanation:

Given data:

Mass of chemical = 100 g

Half life = 8 days

mass left after 40 days = ?

Solution:

First of all we will calculate the total half life's,

half life's = T (elapsed) / T half life

half life's = 40 / 8 = 5

starting mass = 100 g

  half life's         1           2          3             4               5

 Mass             100/2    50/2      25/2       12.5/2       6.25/2

                         50 g        25 g        12.5 g      6.25 g        3.125 g