Question

Half of the substance to remain is called the half-life of the substance.

Answer 1

Answer:

Instructions are below.

Step-by-step explanation:

To calculate the final amount if a given substance, we need to use the following formula:

final amount= initial amount / (2^n)

n= elapsed time / half-life

For 20 years:

n= 20/10= 2

Final amount= 200/(2^2)

Final amount= 50 grams

For 60 years:

n= 60/10= 6

Final amount= 200/ (2^6)

Final amount= 3.125 grams

To calculate the elapsed time it is more complicated:

elapsed time= ln(ending amount/beginning amount) / (-decay constant)

ln= natural logarithm

decay constant= ln(2) / half-life

decay constant= 0.0693

elapsed time= ln(1.03/200) / (-0.0693)

elapsed time= 76.028

Prove:

n= 76.02/10= 7.602

Final amount= 200/(2^7.602)= 1.03 grams