The first model represents the proton and neutron distribution in the nucleus of four helium isotopes. The second image shows the entry for helium in the periodic table. Based on the information in the periodic table, which is the most common isotope of helium?

Helium exist as an isotope, its most common isotope is the one that is placed on the periodic table. The helium atom on the periodic table has two electrons, two protons and two neutrons. The proton and the neutron are located inside the nucleus, this means that two protons and two neutrons can be found inside the helium nucleus. Thus, in the pictures given above, the correct picture is the one that contain four particles.

Explanation:

"1. it should be, it has been for about 20 years, and it's really not much different in the end than breeding animals to have particular traits. there are always concerns about genetically engineered animals/plants affecting the environment in unexpected negative ways, but i can't think of an example where the fears didn't turn out to be baseless.  

first, as you point out, it would be a great advance in pharmacology, to be able to tailor drugs and their doses to me. the pros involve better medical treatment. the cons involve privacy issues like insurance companies denying coverage to people with genetic risk factors. looking at dna markers wouldn't affect the frequency of genetic diseases, but it would allow detection of them earlier. and ok, actually i suppose that if people used this information to avoid having children with genetic diseases, some might decrease in frequency."