11. phosphorus-32 is radioactive and has a half life of 14 days. how much of a 124 mg sample of phosphorus-32 is present after 56 days? a) 7.75 mg b) 15.5 mg c) 31.0 mg d) 62.0 mg

The correct answer is Option A.

Explanation:

All the radioactive decay processes follows first order kinetics.

To calculate the rate constant for a reaction, we use the equation:

where,

k = rate constant for a reaction

= half life of a reaction = 14 days

Putting all the values in above equation, we get:

To calculate the amount of sample left, we use the equation:

where,

N = amount of sample left after time 't'

= initial amount of the sample = 124 mg

k = rate constant of the reaction =

t = time taken = 56 days

Putting values in above equation, we get:

Hence, the correct answer is Option A.

- "the choice that is not an indicator of a chemical change is "state of matter changes". more common than not, chemical reactions produce energy in the form of light or heat. along with energy, they also produce a new substance called the product that could be in any state of matter (solid, gas, or liquid)."