A photon has an energy of 2.09×10^-18 kJ .What is its wavelength?​

wavelength= 1.05 × 10^ -46 m

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

3. dark matter

empty space could also be a simple vacuum