The maximum number of possible electrons in a subshell with $n=3$ and $l=2$ is

The uncertainty in position and velocity of a particle in motion are $1 \times 10^{-8} \mathrm{~m}$ and $6.627 \times 10^{-20} \mathrm{~m} / \mathrm{s}$, respectively. The mass of the particle is ( $h=6.627 \times 10^{-34} \mathrm{Js}$ )

In the two elements, ${ }_{Z_1} A^{M_1}$ and ${ }_{Z_2} B^{M_2}$, the following relations are true. $M_1 \neq M_2$ and $Z_1 \neq Z_2$ but $M_1-Z_1=M_2-Z_2$. These elements are ( $M$ is atomic weight, $Z$ is atomic number)

The correct order of decreasing energy for the electrons whose quantum numbers $n$ and $l$ are given below, is

A. $n=5$ and $l=2$

B. $n=5$ and $l=0$

C. $n=4$ and $l=3$

D. $n=4$ and $l=1$