The thermometric properties of the thermocouple is that is
Answer Details
The correct thermometric property of a thermocouple is that its "e.m.f. changes with temperature." A thermocouple is a device used to measure temperature, and it works by generating a small electrical voltage in response to changes in temperature. This voltage is called an electromotive force or "e.m.f."
The amount of voltage generated by a thermocouple depends on the difference in temperature between its two junctions. As the temperature changes, the e.m.f. also changes, and this change can be measured and used to determine the temperature.
The other options given in the question are not correct for a thermocouple. Resistance, volume, and pressure can all change with temperature, but they are not the primary properties that are used to measure temperature with a thermocouple.