The radius of second orbit of hydrogen atom is same as that of orbit ( n ) of an ion ( x ). n and x are respectively

• A

  $4, \mathrm{Be}^{2+}$
• B

  $3, \mathrm{Li}^{2+}$
• Correct answer
  C

  $4, \mathrm{Be}^{3+}$
• D

  $2, \mathrm{He}^{+}$

Hence, the correct answer is option: 'C'.