Answer
$$\therefore p = 5.43\times 10^{-27}\text{ kg.m/s}$$
Work Step by Step
The momentum of a photon is given by the equation:
$$p = \frac{h}{\lambda}$$
Given
$\lambda = 122\text{ nm }=122\times 10^{-9}\text{ m}$
$$\therefore p = \frac{6.67\times 10^{-34}}{122\times 10^{-9}} = 5.43\times 10^{-27}\text{ kg.m/s}$$
