MCQ
The energy associated with the first orbit in the hydrogen atom is $-2.17 \times 10^{-18} J /$ atom. What is the energy associated with the fifth orbit?
  • $8.68 \times 10^{-20} Js$
  • B
    $3.72 \times 10^{-20} Js$
  • C
    $5.72 \times 10^{-20} Js$
  • D
    $7.72 \times 10^{-20} Js$

Answer

Correct option: A.
$8.68 \times 10^{-20} Js$
(a) $8.68 \times 10^{-20} Js$
Explanation: The energy of first (Bohr) orbit in hydrogen atom $=-2.17 \times 10^{-18} Jatom ^{-1}$ The energy of the fifth orbit will be given by $E_n=E_1 \times \frac{Z^2}{N^2}$
$
E_5=\frac{-2.17 \times 10^{-18}}{5^2}=8.68 \times 10^{-20} Jatom^{-1}
$

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