Phosphorus-32 (radioactive) has __________ than phosphorus-35 (normal).

The isotope Carbon-14 has a half-life of 5,730 years. How many years must pass for a sample of Carbon-14 to break down to ¼ of its original amount?

a) 5,730 years 

b) 17,190

c) 11,460

d) 2,865

What is TRUE about carbon-13 and carbon-14?

a) They are isotopes.

b) They have the same mass number.

c) They have the same number of neutrons in their nuclei.

d) They behave differently in biological reactions.

e) None of the above are true.

How are Carbon-13 and Nitrogen-15 respectively different from the more abundant isotopes Carbon-12 and Nitrogen-14?  Carbon-13 and Nitrogen-15 _______________:

a) Each have an extra neutron.     

b) Each have an extra proton.     

c) Each have one less neutron.

d) Each have one less proton.      

e) Each have one less electron.