What is the mass of elctron ?

The electron has a rest mass of approximately 9.109 × 10^-31 kilograms or 0.511 MeV/c². This is one of the fundamental constants of physics and is crucial in atomic and nuclear physics. The mass is incredibly small, which is why electrons can easily move and form electric currents. Option A correctly represents this value, while other options have either wrong coefficients, wrong signs, or wrong exponents.