Question

The principal quantum number of an atom is related to the:
A) Size of the orbital
B) Spin angular momentum
C) Orientation of the orbital in space
D) Orbital angular momentum

Answer 1

Hint: Principal quantum number tells about each shell present in atom.
The principal quantum number is represented by ‘n’ and n can have the value from 1, since at least one shell will be present in an atom.

Complete answer:
So first let’s analyze the question and find the requirements of the question. The question is asked about the principal quantum number and we have to comment which options are true regarding the principal quantum numbers.
Before solving the question, let’s brush up our memory about the quantum numbers which we study in the branch of physical chemistry.
So in quantum mechanics, we can see that there are four quantum numbers discussed.
So the four quantum numbers are:
1) Principal quantum number which is represented as n and has a value from 1, (n=1, 2,3etc).
2) Azimuthal quantum number which is represented as l and has the values 0 to (n-1).
3) Magnetic quantum number which is represented as m and has a value –l to +l
4) Spin quantum number which is represented as s and has values s=$\dfrac{+1}{2}$and $\dfrac{-1}{2}$
So now let’s discuss the solution for the question.
The question is about the principal quantum number and let’s discuss in detail the principal quantum number of an atom.
Principal quantum number as said above is represented by n and has the values n=1, 2, 3, 4 etc.
It gives us the data of, the number of shells present in an atom, the value of n is equal to the numbered shells that atoms possess.
Since it gives the number of shells, we can get an idea about the size of an atom.
It also gives the probable energy levels of the electron.

So we can conclude that the correct answer for this question is option (A).

Note:
Spin angular momentum is given by the spin quantum number, it gives the spin of the electrons in an atom,
Magnetic quantum number, m value gives the orientation of the orbitals in space.
Orbital angular momentum is given by the azimuthal quantum number and is also called as the orbital quantum number.