Question

Neon gas is generally used in the sign boards. If it emits strongly at 616 nm, calculate (a) the frequency of emission, (b) distance traveled by this radiation in 30 s (c) energy of quantum and (d) number of quanta present if it produces 2 J of energy.

NCERT Class XII
Chemistry - Main Course Book I

Chapter 2. Structure of Atom

Answer 1

 λ = wavelength = 616 nm
frequency of an electro magnetic radiation = f = c / λ
     f = 2.98 * 10⁸ / 616 * 10⁻⁹  =  4.837  * 10¹⁴ Hz

distance = 2.98 * 10⁸ m/sec * 30 sec = 8.94  * 10⁹  meters
           = 8,940,000 km

energy in one photon or quantum :  E = h f = 6.626 * 10⁻³⁴ * 4.837 * 10¹⁴
               =  3.205 * 10⁻¹⁹ J  = 2 eV

number of quanta  = energy / energy per quantum
                   = 2 J / 3.205 * 10⁻¹⁹
                   =  6.239 * 10¹⁸     number of photons or quanta

Answer 2

Answer:

I hope this helps you

Explanation: