The light produced by the electron in strontium has a wavelength of 608 nm. how much energy must be added to strontium to get it to produce this wavelength

According to Einstein the energy of photon is given by the equation,

E = hν = h . c/λ

where h is Planck's constant, c is the speed of light, ν is the frequency of light and λ is the wavelength of light.  

Given, wavelength = 608 nm = 608 x 10⁻⁹ m  

Conversion factor: 1 nm = 10⁻⁹ m  

c = 3 x 10⁸ m/s

h = 6.626× 10⁻³⁴ J.s

Substituting the data into the equation we get,  

E = h . c/λ

E = 6.626× 10⁻³⁴ J.s x (3 x 10⁸ m/s) / 608 x 10⁻⁹ m  

E =  3.27 x 10⁻¹⁹J

3.27 x 10⁻¹⁹J  energy must be added to strontium to get it to produce 608 nm wavelength.

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e