How many sublevels are present in the second shell (n = 2) of an atom?

• A. 3
• B. 2
• C. 1
• D. 4

Answer: (B)

Verified step by step guidance

1. Recall that the principal quantum number \(n\) represents the shell number in an atom, and it determines the energy level of the electrons.
2. Understand that for each shell \(n\), the possible sublevels are determined by the azimuthal quantum number \(l\), which can take integer values from \$0\( to \)n-1$.
3. For \(n = 2\), the possible values of \(l\) are \$0\( and \)1$, which correspond to the sublevels 's' and 'p' respectively.
4. Count the number of sublevels by counting the allowed \(l\) values: since \(l = 0\) and \(l = 1\), there are 2 sublevels in the second shell.
5. Therefore, the second shell (\(n=2\)) contains 2 sublevels: the 2s and 2p sublevels.