NEET Chemistry — Structure of Atom

The radius of the second orbit of a hydrogen atom is $2.116 \times 10^{-10} \, \text{m}$. What is the velocity of the electron in the fourth orbit? ($v_1$ for H = $2.19 \times 10^6 \, \text{m s}^{-1}$)

The ionization energy of $\text{Li}^{2+}$ from its ground state is how many times that of a hydrogen atom? ($E_H = 2.18 \times 10^{-18} \, \text{J}$)

Which of the following has the same number of neutrons as $^{40}_{18}\text{Ar}$?

A metal has a work function of $2.5 \, \text{eV}$. What is the threshold wavelength? ($h = 6.626 \times 10^{-34} \, \text{J s}$, $c = 3.0 \times 10^8 \, \text{m s}^{-1}$, $1 \, \text{eV} = 1.6 \times 10^{-19} \, \text{J}$)

The uncertainty in position of a proton is $1.5 \times 10^{-11} \, \text{m}$. What is the minimum uncertainty in its momentum? ($h = 6.626 \times 10^{-34} \, \text{J s}$)