The elements whose electron configurations end with f electrons are in the Lanthanide and Actinide series: those long series at the bottom of the Periodic Table (see image).
The atoms are adding electrons into f orbitals, but the f electrons are not always the last electrons in the electron configuration.
For example, the electron configuration of Eu is [Xe]6s²4f⁷, but that of Gd
is [Xe] 6s²4f⁷5d.
I have blocked off in <em>red</em> all the <em>exceptions</em> like Gd.
Answer:
The value is 
Explanation:
From the question we are told that
The equation is 
The temperature is ![T = 25^oC = 298 K [room \ temperature ]](https://tex.z-dn.net/?f=%20T%20%3D%2025%5EoC%20%3D%20%20298%20K%20%20%20%5Broom%20%20%5C%20temperature%20%5D)
The emf at standard condition is 
Generally at the cathode

At the anode

Generally for an electrochemical reaction, at room temperature the Gibbs free energy is mathematically represented as

Here n is the no of electron with value n = 6
F is the Faraday's constant with value 96487 J/V
=>
=> 
This Gibbs free energy can also be represented mathematically as

Here R is the cell constant with value 8.314J/K
K is the equilibrium constant
From above
=> 
Generally antilog = 2.718
=>
=> 
5C₂ + 4SO₂ ------> 2CS₂ + 8CO
mole ratio of C₂ : CS₂
= 5 : 2
∴ since C₂ contains 8 moles
then CS₂ contain

moles
= 3.2 moles
A = mass number, A = protons + neutrons
Z = atomic number, Z = protons
neutrons = A - Z
neutrons = 18 - 8 = 10