According to the Aufbau principle,what is the correct order of energy for $3d$,$4s$,and $4p$ orbitals?

In a multielectron atom,which of the following orbitals described by three quantum numbers will have the same energy in the absence of electric and magnetic fields?
$A: n=1, \ell=0, m_{\ell}=0$
$B: n=2, \ell=0, m_{\ell}=0$
$C: n=2, \ell=1, m_{\ell}=1$
$D: n=3, \ell=2, m_{\ell}=1$
$E: n=3, \ell=2, m_{\ell}=0$
Choose the correct answer from the options given below:

The quantum numbers for the outermost electron of an element are given as $n = 2, l = 0, m = 0, s = +\frac{1}{2}$. The element is

Consider the ground state of chromium atom $(Z=24)$. How many electrons are with Azimuthal quantum number $l=1$ and $l=2$ respectively?

Among the following,the incorrect statement is

The electronic configurations of ${}_{24}Cr$ and ${}_{29}Cu$ are abnormal because $:-$