Most portable extinguishers provide how many seconds of chemical discharge?

Answer: B — 8-10 seconds

The main idea here is how long a typical portable fire extinguisher will spray once you pull the trigger. For most portable extinguishers, you get about eight to ten seconds of discharge. That duration matches the size and contents of common handheld units, providing a quick, effective burst to knock down a small fire and give you a moment to assess the situation, retreat if necessary, or call for help. Using short bursts helps conserve the agent and keeps visibility for you as you fight the fire. Longer discharge times are usually seen with larger or specialized extinguishers, while shorter times would not give you enough material to affect a small fire.