Breaking glass is an example of a physical change because if you break it, it is still glass.
Explanation:
an acid will give away a proton and become a conjugate base.
A base will accept a proton and become a conjugate acid.
1) Carbon-13:
Proton-6 Neutron-7 Electron-6
2)Atomic mass of element X:
(55*10+56*20+57*70)/100=56.6