When the azimuthal quantum number has a value of $l = 0$,the shape of the orbital is

The number of electrons with $(n+\ell)$ values equal to $3, 4$ and $5$ in an element with atomic number $(Z) = 24$ are respectively $(n =$ principal quantum number and $\ell =$ azimuthal quantum number).

The maximum number of electrons that can be filled in the shell with the principal quantum number $n=4$ is

Arrange the following orbitals in increasing order of energy based on the given values of principal quantum number $(n)$ and azimuthal quantum number $(l)$:
$(1) n = 4, l = 1$
$(2) n = 4, l = 0$
$(3) n = 3, l = 1$
$(4) n = 3, l = 2$

Which of the following rules states that an orbital can hold a maximum of two electrons?

Assertion $(A)$: Atoms with completely filled and half-filled subshells are stable.
Reason $(R)$: Completely filled and half-filled subshells have symmetrical distribution of electrons and have maximum exchange energy.
The correct answer is: