NEET Chemistry — Structure of Atom

The uncertainty in the position of an electron is \( 1.0 \times 10^{-10} \, \text{m} \). What is the minimum uncertainty in its velocity? (\( h = 6.626 \times 10^{-34} \, \text{J s} \), \( m_e = 9.1 \times 10^{-31} \, \text{kg} \))

A photon has an energy of \( 4.968 \times 10^{-19} \, \text{J} \). What is its wavelength in nanometers? (\( h = 6.626 \times 10^{-34} \, \text{J s} \), \( c = 3.0 \times 10^8 \, \text{m s}^{-1} \))

How many spectral lines are observed when an electron falls from \( n = 4 \) to \( n = 2 \) in a hydrogen atom?

An electron in \( \text{Li}^{2+} \) is in the \( n = 2 \) state. What is its energy in joules? (\( E_1 \) for H = \( -2.18 \times 10^{-18} \, \text{J} \))

A metal has a threshold frequency of \( 4.8 \times 10^{14} \, \text{Hz} \). What is the kinetic energy of an electron ejected by light of frequency \( 7.2 \times 10^{14} \, \text{Hz} \)? (\( h = 6.626 \times 10^{-34} \, \text{J s} \))