Questions with the keyword 'rainbow'

• why is the pH scale so similar to the rainbow?? which came first?? by cc2107 and 1 other. to David, Jonathan, Pete, Sam Comments: (No comments so far )
• why is the rainbow 7 different colours? by kamilo12 and 3 others. to David, Jonathan, Ou, Pete, Sam, Mus, Tess, Yue, Faye Comments: (No comments so far )