Answer
a)No. of protons = 79
No. of electrons = 78.
b) No. of protons = 79
No. of electrons = 76.
c) No. of protons = 50
No. of electrons = 48
d) No. of protons = 50
No. of electrons = 46
Work Step by Step
Atomic number of Au = 79.
Hence, no. of protons is 79.
Also no. of electrons is 79 for neutral Au atom so that the overall charge is zero for the atom.
Now, for $Au^{+}$ one electron is emitted. So, the no. of electron will be 79-1 = 78.
For $Au^{3+}$ three electrons are emitted. So, the no. of electron will be 79-3 = 76.
Atomic number of Sn = 50.
Hence, no. of protons is 50.
Also no. of electrons is 50 for neutral Sn atom so that the overall charge is zero for the atom.
Now, for $Sn^{2+}$ two electrons are emitted. So, the no. of electron will be 50-2 = 48.
For $Sn^{4+}$ four electrons are emitted. So, the no. of electron will be 50-4= 46.
