Bohr's Model — Prelims Questions

According to Bohr's model, the ratio of the radius of the third orbit to the radius of the first orbit for a hydrogen atom is:

The energy of an electron in the first Bohr orbit of a hydrogen atom is $-13.6 \text{ eV}$. What is the energy of the electron in the second Bohr orbit of a $He^+$ ion?

Which of the following statements is NOT a postulate of Bohr's model of the atom?

Calculate the wavelength of the photon emitted when an electron in a hydrogen atom transitions from $n=3$ to $n=1$. (Given: Rydberg constant $R_H = 1.097 \times 10^7 \text{ m}^{-1}$)

The velocity of an electron in the first Bohr orbit of a hydrogen atom is $v$. What will be the velocity of an electron in the second Bohr orbit of a $Li^{2+}$ ion?

What is the ionization energy of a $He^+$ ion in its ground state?