In $H$ atom,an orbit has a diameter of about $16.92 \ \mathring{A}$. What is the maximum number of electrons that can be accommodated in this orbit?

Consider the following statements:
$(a)$ Photon is a positively charged nuclear particle
$(b)$ Size of nucleus is very small as compared to the size of atom
$(c)$ Photoelectric effect and diffraction show particle nature of light
$(d)$ Planck's constant has same dimensions as angular momentum
The correct statements is/are:

The shape of the probability distribution curve for the $2s$ orbital is .........

In which of the following transitions is one quantum of energy emitted?

Which of the following arrangements of electrons is most likely to be stable?

Which of the following graphs represents one node?