Question

establish a relation between an electronvolt and the si unit of the physical quantity which it measures

Answer 1

HELLO FRIEND!!
Rajdeep here....

Do you know what?
Electron volt is the unit which measures the physical quantity ENERGY.

=> Energy is the capacity of a body to do work.

=> 1 eV is the energy gained by an electron when it is accelerated through a potential difference of 1 Volt.

=> Now, the SI unit of energy is Joule (J) and your question is to derive a relation between Electron-Volt (eV) and Joule. Here's your answer:

$1 eV = 1.6 \times 10^{-19} J$
Or 1 eV = 1.6 × (10)^(-19) Joule

Thanks!!