Which of the experimental chemical compounds appears to have the broadest range of microbicidal activity? The narrowest range of microbicidal activity? (depends entirely on your results

The chemical compounds that appear to have the broadest reange are the hydrogen peroxide and chlorine bleach. The narrowest range one is isopropyl alcohol.

Can the disinfection period(exposure time) be arbitrarily increased?

No, all the microbes will not be destroyed during the same time. However, toxicity and environmental conditions should be considered in the assessment time for disinfection period.

A household cleanser is labeled germicidal. Explain what this means to you.

When a household cleanser is labeled germicidal, this means that the product can be distructive to pathigenic microorganisms.