Question

Principal quantum number (n) is represented with

• A. 0,1,2,3,. ..
• B. K, L, M,...
• C. X, Y, 2, ..
• D. A, B, C, ....

Answer 1

The Correct Option is B

Correct answer: K, L, M,... 

Explanation:
The principal quantum number (\( n \)) determines the main energy level or shell of an electron in an atom. These shells are designated by the letters: 

- \( n = 1 \rightarrow \) K shell
- \( n = 2 \rightarrow \) L shell
- \( n = 3 \rightarrow \) M shell
- \( n = 4 \rightarrow \) N shell
and so on. 

Hence, the correct answer is: K, L, M,...