The maximum number of sub-levels, orbitals and electrons in $N$ shell of an atom are respectively

In a multi-electron atom,which of the following orbitals have the same energy in the absence of magnetic and electric fields? $(a) n = 1, l = 0, m = 0, (b) n = 3, l = 0, m = 0, (c) n = 2, l = 1, m = 1, (d) n = 3, l = 2, m = 1, (e) n = 3, l = 2, m = 0$

The atomic number of an element is $17$. The number of orbitals containing electron pairs in its valence shell is

The sum of paired electrons present in $l = 2$ orbitals for the species $Fe^{2+}$,$Co^{2+}$,and $Ni^{2+}$ is .......

$(i)$ An atomic orbital has $n=3$. What are the possible values of $l$ and $m_l$?
$(ii)$ List the quantum numbers ($m_l$ and $l$) of electrons for $3d$ orbital.
$(iii)$ Which of the following orbitals are possible? $1p$,$2s$,$2p$,and $3f$.

In a multi-electron atom,which of the following orbitals described by the three quantum numbers will have the same energy in the absence of magnetic and electric fields?
$1. n = 1, l = 0, m = 0$
$2. n = 2, l = 0, m = 0$
$3. n = 2, l = 1, m = 1$
$4. n = 3, l = 2, m = 0$
$5. n = 3, l = 2, m = 0$