5.7 gallons
if you divide 279 / 49 it = 5.69, which you would just round up to 5.7
wavelenghts are lengths. they are measured in distances.
The main use of litmus is to test whether a solution is acidic or basic. Blue litmus paper turns red under acidic conditions and red litmus paper turns blue under basic or alkaline conditions, with the color change occurring over the pH range 4.5–8.3 at 25 °C (77 °F).
