NEET 2016 Physics and Chemistry Paper 2

Quantum numbers are used to describe completely the position, energy, space orientation and spin of an electron in an atom.There are four quantum numbers: the principal quantum number $(n)$, the azimuthal (angular momentum) quantum number $(l)$, the magnetic quantum number $(m_l)$ and the spin quantum number $(m_s)$.Here, $n=3$ and $l=1$ are given.The principal quantum number $n=3$ shows that the electrons belong to the third energy level (third shell).The azimuthal quantum number $l$ fixes the subshell, and $l=0,\,1,\,2,\,3$ correspond to the $s,\,p,\,d,\,f$ subshells respectively.Since $l=1$, the given values correspond to a $p$ subshell, that is, the $3p$ subshell.The number of orbitals present in a subshell is given by the formula $(2l+1)$.Substituting $l=1$, we get $(2l+1)=3$, so the $3p$ subshell has three orbitals $(m_l=-1,\,0,\,+1)$.Each orbital can accommodate a maximum of two electrons of opposite spin.Therefore, the maximum number of electrons that can fit in the orbital set with $n=3$ and $l=1$ is $3\times 2 = 6$.Hence, the correct answer is 6.