I need help with this someone help me?

Asample of a gaseous substance changes into a liquid

One day, after pulling down your window shade, you notice that sunlight is passing through a pinhole in the shade and making a small patch of light on the far wall. you see that the patch of light seems to be a circular diffraction pattern. it appears that the central maximum is about 1 cm across and you estimate that the distance from the window shade to the wall is about 3 m. what is (a) the average wavelength of sunlight? (b) the diameter of the pinhole?

Which of the following are used in an electrochemical cell? a. electrodes b. electrolyte c. terminals d. all of the above