For the hydrogen atom where Rh=2.18*10^-18 J, the wavelength of the transition from the ground state to the n=3 state is_____?

Answer 1

First I don't think R_H = 2.180E-18 J.
R_H = 1.09737E7
1/wavelength = 1.09737E7(1/1 - 1/9) and solve for wavelength in meters.
If you want to use that 2.18E-18 J number, that can be done this way.
delta E = 2.180E-18J x (1/1 - 1/9)
Then E = hc/wavelength and solve for wavelength.