What temperature must ammonia (NH3) be kept below to prevent exceeding its critical temperature?

Ammonia's critical temperature is a crucial value that determines the conditions under which it can exist as a liquid. For ammonia, this critical temperature is approximately 271.4 degrees Fahrenheit. To avoid exceeding this critical temperature and maintain ammonia in a liquid state under pressure, it must be kept below this specified threshold.

When ammonia is heated above this temperature, it transitions to a gaseous state regardless of the pressure applied, which is essential knowledge for handling and storing ammonia safely in various industrial applications. Therefore, keeping the temperature below 271.4 degrees Fahrenheit ensures that the ammonia remains in a liquid state, which is vital for its use in refrigeration and other processes where it acts as a refrigerant or in chemical manufacturing.

The other options suggest temperatures that either exceed or remain too close to the critical temperature, which would not effectively maintain ammonia in its desired liquid state for safe handling and operational efficacy.