Half life worksheet answer key 1. how long does it take a 100.00g sample of as-81 to decay to 6.25g?

132 seconds ( 2 Minutes 12 seconds).

Explanation:

Half life is basically the time it takes for a compound to decay to half of it's original mass.

In this problem, the compound is As. The half life of As-81 is 33 seconds. This means it takes 33 seconds for 100 g of As-81 to decay to 50g. The question however id to find the time it takes for it to decay to 6.25g.

We find how many half life's it would take,

100 --> 50 (First half life)

50 --> 25  (Second half life)

25 --> 12.5 (Third half life)

12.5 --> 6.25 (Fourth half life)

This means the total time is 4 * 33 (Half life) = 132 seconds ( 2 Minutes 12 seconds).

is there multiple choice answers?

a: 45.9 meters

b: 4.29 seconds

step-by-step explanation:

a: h(t)=1/2(-9.8)(3)^2+0(3)+90

h(t)=-4.9(3)^2+90

h(t)=-44.1+90

h(t)=45.9 meters

b: 0=1/2(-9.8)(t^2)+0t+90

0=-4.9t^2+90

-90=-4.9t^2

18.37=t^2

t=4.29 seconds

in the second question, the numbers aren't exact, but they're a close approximation.