Which of the following particles has a mass similar to that of an electron?

$A$ Laser light of wavelength $660\,nm$ is used to weld Retina detachment. If a Laser pulse of width $60\,ms$ and power $0.5\,kW$ is used,the approximate number of photons in the pulse are: [Take Planck's constant $h = 6.62 \times 10^{-34}\,Js$]

The energy $E$ and momentum $p$ of a moving body of mass $m$ are related by a specific equation. Given that $c$ represents the speed of light,identify the correct equation.

The frequency of a photon having energy $100 \ eV$ is $(h = 6.6 \times 10^{-34} \ J \cdot s)$.

The ratio of the power of a light source $S_1$ to that of the light source $S_2$ is $2$. $S_1$ is emitting $2 \times 10^{15}$ photons per second at $600 \ nm$. If the wavelength of the source $S_2$ is $300 \ nm$,then the number of photons per second emitted by $S_2$ is . . . . . . $\times 10^{14}$.

The wavelength of an electron and a photon are equal. If the energy of the photon is $E$ and the momentum of the electron is $p$,what is the value of $p/E$?