Sodium vapour lamps used for public lighting emitting 589 nm yellow light. Calculate the energy emitted by: an excited atom when it generates a photon at this wavelength and calculate the energy emitted by 0.1mol of excited Sodium atom at this wave length?

Answer 1

You may want to spell chemistry right.
E = hc/wavelength
for one atom.
That x 6.02E22 atoms for 0.1 mol.