In which of the following will isotopes of an element always differ?

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.  

The atomic number of nitrogen is 7. Nitrogen-15 has a greater mass number than nitrogen-14 because the atomic nucleus of nitrogen-15 contains ________.

a) 7 neutrons.

b) 8 neutrons.

c) 8 protons.

d) 15 protons.

Radioactive isotopes are utilized for all of the following except:

a) Dating fossilized material of once living things.

b) Radiation treatment to slow or stop the development of cancer cells.

c) Labeling regions of the body with radioactivity for special imaging techniques.

d) All of the above.

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