Answer:
wavelength= 1.05 × 10^ -46 m
Step-by-step explanation:
the formula : λ= hc/E
where; "h" = Planck's constant [6.626 × 10^ -34]
c= speed of light [3.0 × 10^ 8]
you first have to convert the energy of the photon to Joules by dividing the constant by 1000
2.09 × 10^ -18 / 1000 = 2.09 × 10^ -21
then you replace you data into the equation
λ= 6.626 × 10^ -34 × 3.0 × 10^ 8 / 2.09 × 10 ^ -21
first multiply the Planck's constant and the speed of light then divide it by the energy which is in "Joules"
:. λ = 1.05 × 10^ -46
hope this helps