If the energies of two light radiations $E_1$ and $E_2$ are $25 \ eV$ and $100 \ eV$ respectively,then their respective wavelengths $\lambda_1$ and $\lambda_2$ would be in the ratio $\lambda_1: \lambda_2=$

The work function of sodium metal is $4.41 \times 10^{-19} \ J$. If photons of wavelength $300 \ nm$ are incident on the metal,the kinetic energy of the ejected electrons will be $\left( \dots \right) \times 10^{-21} \ J$. (Given: $h = 6.63 \times 10^{-34} \ J \cdot s; c = 3 \times 10^{8} \ m/s$)

Match the principles given in List-$I$ with their discoverers given in List-$II$.

List-$I$	List-$II$
$(1)$ Exclusion Principle	$(A)$ Hund
$(2)$ Multiplicity Rule	$(B)$ Heisenberg
$(3)$ Uncertainty Principle	$(C)$ Einstein
$(4)$ Quantum Theory	$(D)$ Planck
	$(E)$ Pauli

The four lowest energy levels of the $H$ atom are shown in the figure. The number of emission lines will be ...... .

When an electron jumps from $n = 5$ to $n = 2$ with all possible transitions,which of the following statements is correct?

The visible range of the hydrogen spectrum contains which of the following series?