<span>the elements in groups1a, 2a, 3a have positive charges according to their group numbers</span>
Answer:The compound created by calcium and chlorine is calcium chloride, and the formula for this compound is CaCl2 .
Explanation:
"As we move through the visible spectrum of violet, blue, green, yellow, orange and red, the wavelengths become longer. The range of wavelengths (400 - 700 nm) of visible light is centrally located in the electromagnetic spectrum (Fig. 1)."
-https://www.asu.edu/courses/phs208/patternsbb/PiN/rdg/color/color.shtml
