Answer:
1/32 = 0.03125 = 3.125%
Explanation:
The nitrogen-16 is an unstable isotope of nitrogen. The isotopes are the elements with the same atomic number but have a different number of mass. It means that they have a different number of neutrons (mass = protons + neutrons).
Because it is unstable, it decays in particles beta(β) and alpha (α), and the time that is necessary to the half of the mass disappear is called half-life which is equal to 7.13 s for nitrogen-16.
The mass that remains (m) can be calculated by:
m = m0/2ˣ, where m0 is the initial mass, and x the number of half-lives.
x = time/half-life time
x = 35.65/7.13
x = 5
Then,
m = 20.00/2⁵
m = 20.00/32
m = 0.625 g
The fraction is the mass that remains divided by the original mass:
0.625/20.00 = 1/32 = 0.03125 = 3.125%
