Answer: b
Explanation:
By adding heat you are adding more energy
The atomic number of calculated as number of protons + number of neutrons. The number of protons are the same as atomic number. This implies that Nitrogen has seven protons. To get the the number of neutron we minus atomic mass from number of protons
that is 14-7=7 neutrons
Answer:

Explanation:
To determine the age, we need to know how much U have become Pb, so first we have to calculate the Pb moles present in a sample:


The percentage of U degradation:


Assuming that the life time is linear:

