How was helium first discovered?

mining of the radioactive element uranium
using spectral analysis of the suns’ emission spectra
hubble obtaining samples from explosions off the surface of the sun
deep sea mining off the coast of texas

Calcium chloride +gold(1) oxide—>

Diffraction is when light is bent around obstructions. which of the these observation about clouds would indicate diffraction? a) after rain storms, you can sometimes see rainbows. b) clouds are white or gray and cannot be seen through. c) on a cloudy day, the temperature tends to be cooler than a sunny day. d) the edges of dark clouds appear lighter. this

Is 9 correct? and can someone me with 10? it’s due tomorrow, you