Answer:

Explanation:
The Hi line of the Balmer series is emitted in the transition from n = 3 to n = 2 i.e.
and 
The wavelength of Hi line of the Balmer series is given by :




So, the wavelength for this line is 550 nm. Hence, this is the required solution.
I think It would be C. Checking a prediction. Sorry if I’m wrong
No, I heavier object will fall much faster than something lighter than it. This is because it’s more dense and hard so it can cut through the air particles quicker than a lighter object which takes longer to cut through the air and fall
Example:
A rock vs a feather
The rock will fall quicker because it’s more dense and falls straight down and the feather will be slower because it flows slowly down through the air particles
Answer:
1.F: About 6*10^14 Hz
2.E: About 4*10^ -19 J
Explanation:
Frequency: We knew that the speed of a wave is its wavelength(λ)* frequency(f, in Hz). By the wave-particle duality we know we can calculate the frequency of light in the same way. So, c=495nm *f, f=c/495nm=> (299,792,458 m/s) / (4.95*10^-7 m)
=6.05*10^14 /s
Energy: The energy photon contains can be calculate by this formula-- E=hf
f is the frequency and h is Planck's constant which is about 6.62 ×10^-34 *m^2*kg/s (after dimensional analysis ) =6.62*10^ -34 J*s.
So, the energy of a blue photon is (6.05*10^14)*(6.62*10^-34)=40.051*10^-20= 4.051*10^-19 J