The answer is A :) your welcome hope this helps
20 mol of NH, can be produce from 30 mol o H2
It is in period 3
It is in group 17
It is a chlorine atom because it has 17 electrons which means the atomic number is 17
<u>Answer:</u> The wavelength of spectral line is 656 nm
<u>Explanation:</u>
To calculate the wavelength of light, we use Rydberg's Equation:

Where,
= Wavelength of radiation
= Rydberg's Constant = 
= Final energy level = 2
= Initial energy level = 3
Putting the values in above equation, we get:

Converting this into nanometers, we use the conversion factor:

So, 
Hence, the wavelength of spectral line is 656 nm