The number of unpaired electrons in $Fe^{3+}$ $(Z = 26)$ is:

The electrons identified by quantum numbers $n$ and $l$ :
$A. n=4, l=1$ $B. n=4, l=0$
$C. n=3, l=2$ $D. n=3, l=1$
can be placed in order of increasing energy as :

Arrange the following atomic orbitals of multi-electron atoms in order of increasing energy.
$A$. $n=3, l=2, m=+1$
$B$. $n=4, l=0, m=0$
$C$. $n=6, l=1, m=0$
$D$. $n=5, l=1, m=+1$
$E$. $n=2, l=1, m=+1$
Choose the correct answer from the options given below:

Which of the following represents the ground state of an atom?

In the following pairs,which orbital experiences greater nuclear attraction?
$(i)$ $4f$ and $5d$ $(ii)$ $4d$ and $5s$ $(iii)$ $7s$ and $5f$ $(iv)$ $7p$ and $5p$
$(v)$ $3d$ and $3f$

Which of the following sets of quantum numbers represents the $19^{\text{th}}$ electron of $Cr$ $(Z=24)$?