The green light emitted by a stoplight has a wavelength of 505 nm. What is the frequency of this photon? (c = 3.00 × 10⁸ m/s).

5.9405*10^14 Hz

Explanation:

Remember the equation c=v*λ

v=frequency

λ=wavelength

By manipulating the equation, we can get it in terms of frequency:

c/λ=v

Now convert wavelength to meters (1nm=m*10^-9)

5.05*10^-7m (2 decimal places were shifted to make the number between 1-10, hence the -7 exponent)

Use the manipulated equation:

(3.00*10^8)/(5.05*10^-7), which yields:

5.9405*10^14 Hz (or s^-1)

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.