Questions at random?

1. How many neutrons are there in the nucleus of the isotope17 g0 of oxygen?


a.9


b.7


c.17


d.8





(please mention formula used)


2. Suppose that a particular sample of wood contains 10^20 atoms of the radioactive isotope ^14C, fror which the half life is about 6000yrs. Approx. how long will it take for all the ^14C atoms to decay to ^14N?


a. an infinite amount of time


b. 6,000yrs


c. 12,000yrs


d. 3,000yrs

Questions at random?
1.


oxygen has 8 protons and mass of 17 in this case so


17-8 = 9 neutrons (a)





2.


a half life means time for it to half in number, however, no matter how many times it halves it will never reach 0 (in theory but in practice this is slightly different)


so the answer is:


a) "an infinite amount of time"
Reply:the answer to 1. is a. isotope O has 8 protons so 8-17=9=%26gt;neutrons.


#2. this is a half life problem so the answer is a. it will take and infinate amount of time to decay because the [14C] is /2 every 6000yrs so it will never =0