What is the nanometers of photon emitted in the process

Question

Assignment:

Q 1. The energy levels of a certain atom have the following pattern:

E₁ = -340eV (n = 1),

E₂ = -85eV (n = 2),

E₃ = -37.78 eV (n = 3), and so on..

An electron drops from n=3 to n=1 in this atom. What is the wavelength in nanometers of the photon emitted in the process? Planck's constant h = 6.626 x 10^-34 Joule-sec. 1eV = 1.6 x 10^-19 Joules.

Q 2. How many photons per second come out of a ruby laser that is giving out 2 milliwatts of power? ( 1 watt = 1 Joule/sec and I eV =- 1.6 x 10^-19 Joules). Look up the web for what wavelength a ruby laser produces.

Q 3. You have three liquids: ethly alcohol, chloroform and ice-cold water. When you mix 100 grams of ethly alocohol at a temperature of T=25 Celsius with 200 grams of ice-cold water T=0 C), the resulting mixture has a temperature Of 5.55 C. When you mix 200 grains of ethyl alcohol at a temperature of T=25 Celsius with 100 grants of chloroform at. T=10 C, the resulting mixture has a temperature of 22.22 C. What is the final temperature when you mix 150 grams of ethyl alcohol at T=15 C with 250 grams of chloroform at T=5 C? (You are given that the specific heat capacity of water is 4.2 J/g.K)