Atoms with certain characteristics are radioactive. Which is least likely to be
radioactive?
A. all atoms with an atomic number under 40
B. all atoms with an atomic number over 83
C. all atoms with twice as many neutrons as protons
C
D. all atoms with half as many neutrons as protons

a.) is the correct answer.

explanation:

when jerome paddle in flowing river towards east the net speed of jerome will increase

so the net speed of jerome will be given as

now the speed of paul will be same as it is given as he is running on the ground

so

so here we can say since the speed of jerome is more so he will win the race

now as we know the distance so the time difference is given as

so jerome will reach first and the time difference will be 203.55 s or 3.4 min