Subtle implications of quantum numbers Question:


  Given the subshells $\ce{1s, 2s, 2p, 3s, 3p}$ and $\ce{3d}$, identify those
  that meet the following descriptions:
  a) has $l=2$ 
  b) Can contain two electrons with spin $m_{s}=\pm\frac{1}{2}$.


For a): from my understanding $l=n-1$. Therefore $\ce{3s, 3p}$ and $\ce{3d}$ should be correct but according to my solutions manual, the answer is only $\ce{3d}$. Why is this so?

For b) The answer is $\ce{2p, 3p}$ and $\ce{3d}$. Why are these the answers?
a) You are wrong. $l=2$ simply means $\ce{d}$-orbitals, thus, only $\ce{3d}$ is the right answer.

b) Assuming that the meaning of the question is to specify subshells that can contain two electrons in the same spin state, i.e. both with $m_s = +1/2$ or both with $m_s = -1/2$, $\ce{s}$-orbitals should indeed be excluded.