Answer:
It will take 15.029 years for element X to reach mass of 260 grams
Step-by-step explanation:
The half life period of radioactive element X is 26 years
The initial mass of radioactive element X is 260 grams
Elapsed time = half life * log (beginning amount /ending amount)/log 2
Substituting the given values, we get
Elapsed time = 26 * log (390/260)/log 2
= 15.209 years
…………………………………………….not really sure about the last question
Its b for sure i worked it out
Step-by-step explanation:
△BAC ≅ △EDF (given)
Therefore,
BC=EF
x-4=19
x=23