After adding an ampule of calcium hypochlorite to water in a Lyster bag, you wish
to determine the chlorine residual using the five parts per million (ppm) plastic
comparator tube. You test a sample with orthotolidine and find that the yellow
color in the sample is lighter than the yellow band around the top of the tube. This
tells you that the chlorine residual is:
a. More than five ppm.
b. Exactly five ppm.
Less than five ppm.
d. At least one ppm.
As they deteriorate, iodine tablets change color. Tablets effective in treating water
a. Light yellow.
d. Dark reddish brown.
What number of iodine tablets is used to purify a quart canteen full of unclear
water for drinking purposes?