Question

Radium has a half-life of 1,620 years. In how many years will a 1 kg sample of radium decay and reduce to 0.125 kg of radium?

1,620 years

3,240 years

4,860 years

6,480 years

Answer 1

your answer would be C because after 0 half lives 1 kg after 1 half life 0.5 kg after 2 half lives 0.25 kg after 3 half lives 0.125 kg so that is three half lives , or 3 times 1,620 years = 4860 years

hope i helped

Answer 2

Using the formula:
elapsed time = half life * log (beginning amount / ending amount) / log 2
= 1620*log(1/0.125)/log2
=1436/0.30
=4786.66

So the closest answer would be 4860 Years