Calculate the frequency if the wavelength is $750 \ nm$.

Which emission transition series is obtained when an electron jumps from $n_2 = \infty$ to $n_1 = 1$?

Give the characteristics of electromagnetic radiation. Give the relation between them.

The work functions $(W_0)$ of $K, Na, Li, Mg$ and $Cu$ are $2.25, 2.30, 2.42, 3.70$ and $4.80 \ eV$ respectively. How many of these metals do not undergo photoelectric effect when a radiation of wavelength $450 \ nm$ is allowed to fall on them? $(1 \ eV = 1.602 \times 10^{-19} \ J)$

The energy required to break one mole of hydrogen-hydrogen bonds in $H_2$ is $436 \ kJ$. What is the longest wavelength of light required to break a single hydrogen-hydrogen bond (in $nm$)?

Assertion : All photons possess the same amount of energy.
Reason : Energy of photon does not depend upon wavelength of light used.