Answer: Mercury-194 is an unstable isotope and hence is radioactive.
Explanation: Mercury-194 is an isotope of mercury, having formula 
Number of protons in this isotope = 80
Number of neutrons in this isotope = 114
This isotope is radioactive in nature and under decay process by Electron Capture.
Electron capture reactions are the reactions in which a proton in a nucleus absorbs an electron and convert it into neutron. The resulting nucleus will have a decreased atomic number and same atomic mass.
Reaction for electron capture of mercury-194 follows:

Copper is an element. So is can't form, but it takes certain types of copper tens of thousands of years depending on where the magma was cooled.
There are 2 types of electricity, static electricity and current electricity
To convert the formula unit to mass, we need to divide the given formula units by Avogadro's number, 6.022 x 10^23 and we get the mole of beryllium nitrate. To convert to mass, we need to multiply the number of moles with the molecular formula of the compound which is 133.022 g/mol.The answer is 0.006185 g or 6.185 mg.
The closest shell (n = 1) can contain a maximum of 2 electrons.