In the first excited state of hydrogen atom, the energy of its electron is -3.4 eV. The radial distance of the electron from the hydrogen nucleus in this case is approximately : (Take 1 eV = 1.6 10^ -19 J, e = 1.6 10^ -19 C and 1 4 _0 = 9 10^ 9 N m^2/C^2)
C. 2.1 10^ -10 m
The total energy of an electron in a hydrogen atom is given by E = - 1 4 _0 e^2 2r Substituting the given values: -3.4 1.6 10^ -19 = - 9 10^9 (1.6 10^ -19 )^2 2r r = 9 10^9 1.6 10^ -19 2 3.4 r = 14.4 10^ -10 6.8 r 2.117 10^ -10 m This is approximately 2.1 10^ -10 m. Answer: 2.1 10^ -10 m
Related: Physics — Atomic Physics · All PYQ Banks