To solve for \( x + y \), where \( x \) and \( y \) are the number of electrons in the 4d orbitals of niobium (Nb) and ruthenium (Ru), respectively, we need to refer to the electron configurations of these elements:
Now, compute \( x + y \):
\( x + y = 4 + 7 = 11 \)
Check that the sum \( 11 \) falls within the specified range \([11, 11]\), confirming that our computed value is correct.
Therefore, the value of \( x + y \) is 11.
Energy of first Balmer line of H-atom is \( x \) kJ. The energy of the second Balmer line of H-atom is _____