The mass number doesn't depends on the number of electrons.
Knowing which element it is and its formal charge, subtract the charge from its atomic number.
It is not possible.
you can find the positive or negative sign and make the new measurement
Not without knowing who made it.
Impossible to answer without knowing who made it.
you can find electrons by subtract the atomic number and atomic mass.
Yes, and in order to find the Number of Neutrons, subtract Atomic Mass from Number Of Protons, the result will be the Number of Neutrons for that atom *No. Of Neutron=Atomic Mass - Number Of Protons
the number of valence electrons is the number group on the table its on
Impossible to answer without knowing who made it. Even then, if data has not been published you will not find out.
there are 5 electrons in boron
No
In a neutral atom the number of electrons is the same as the atomic number, which is the number of protons in the nucleus.