Structure of the Atom · Paper 1 — Free Physics HL Practice Questions

A nucleus contains 6 protons and 8 neutrons. Which statement correctly identifies the mass number of this nucleus?

An electron in a hydrogen atom is in the $n = 2$ energy level. A photon of wavelength $\lambda = 486\text{ nm}$ is incident on the atom. The first four energy levels of hydrogen are $E_1 = -13.6\text{ eV}$, $E_2 = -3.4\text{ eV}$, $E_3 = -1.5\text{ eV}$, and $E_4 = -0.85\text{ eV}$. Which statement correctly describes whether this photon is absorbed?

Iodine-131 has a mass number of 131 and contains 78 neutrons in its nucleus. Which quantity correctly identifies the atomic number of this isotope?

Naturally occurring boron consists of two stable isotopes: $^{10}$B with atomic mass $10.01\text{ u}$ and $^{11}$B with atomic mass $11.01\text{ u}$. The relative atomic mass of naturally occurring boron is $10.81\text{ u}$. What is the percentage abundance of $^{10}$B?