Please help with this chem question!

The most efficient way to establish the best possible economizer position is to measure

Which statement is true about the part of the electromagnetic spectrum that human eyes can detect? it contains only the colors of the rainbow and television waves. o it is divided into seven ranges of wavelengths. it contains ultraviolet, visible, and infrared light. it is divided into nine ranges of wavelengths.

If i had 2 m naoh solution, what does the 2 m stand for? 2 molar, but 2 of a solute in 1