The energy and radius of electron present in second orbit of `He^+` respectively are

Options

A. `-2.18 times 10^-18 J, 105.8 pm`
B. `-4.36 times 10^-18 J, 52.9 pm`
C. `-1.09 times 10^-18 J, 105.8 pm`
D. `-8.72 times 10^-18 J, 211.6 pm`

Answer

A

Explanation

Answer(1) Energy of an electron, `E_n = -13.6 z^2/n^2 eV`
For He atom, Z = 2 .
` E_n = -13.6 (2)^2/(2)^2 eV` .
= `-13.6 (1.6 xx 10^-19J) [because 1eV = 1.6 xx 10^-19J]` .
`therefore "Energy", E_n = -2.18 xx 10^-18 J`.
Radius of an electron, r = `0.529 xx n^2/ z A^@` .
= `0.529 xx (2^2)/1 xx 10^2 pm` .
[`therefore 1A^@ = 10^2 pm`] .
`therefore Radius, r = 105.8pm`