How much of a sample remains after three half-lives have occurred?
1/16 of the original sample
119 of the original sample
1/8 of the original sample
1/3 of the original sample

1/8 of original sample.

Explanation:

Consider your final amount is 100 g.

After three half lives:

at 0 = 100 g

1 half life = 100/2  = 50 g

2 half life = 50/2 = 25 g

3 half life = 25/2 = 12.5 g

Know multiply the amount after three half lives with 8.

12.5 g × 8 = 100 g

So, after three half lives 1/8 of original sample is present.

i believe it is a.) released into

explanation:

definition

                    entropy is a measure of the randomness or the extent of disorder of a chemical process.

                      enthalpy is a measure of the heat change of a reaction occurring at a constant pressure.

measurement units:

                        entropy is measured in joule per kelvin (jk⁻¹)   whereas enthalpy is measured in joule per mole (jmol⁻¹)

requirements:

                            entropy has no requirements or limits, and its change is measured by the division between the heat change of the chemical process and the temperature.

                              in contrast, enthalpy can only be related to the heat change of the reaction under standard conditions.