Work function $(W_0)$ values of six metals (in $eV$) are given below: $Li: 2.42, Mg: 3.7, Cu: 4.8, Ag: 4.3, K: 2.25, Na: 2.3$. How many of the above metals do not eject the electrons when they are made to strike with radiation of wavelength $400 \text{ nm}$? $(h = 6.62 \times 10^{-34} \text{ Js})$

The number of incorrect statement/s about the black body from the following is $........$.
$(A)$ Emit or absorb energy in the form of electromagnetic radiation
$(B)$ Frequency distribution of the emitted radiation depends on temperature
$(C)$ At a given temperature,intensity vs frequency curve passes through a maximum value
$(D)$ The maximum of the intensity vs frequency curve is at a higher frequency at higher temperature compared to that at lower temperature

In the hydrogen spectrum,the various lines of the Lyman series lie in the $.......$ region.

Electromagnetic radiation with maximum wavelength is

Calculate the energy of one mole of photons of radiation whose frequency is $5 \times 10^{14} \ Hz$.

$\alpha$-rays have high ionization power because they possess