(i)What is thermo emf?
(ii)What is neutral temperature?
(iii)What is thermocouple?
(iv)What is the rate of increase of thermo-e.m.f. with
temperature at the neutral temperature of a
thermocouple will be?

The e.m.f. set up in a thermocouple , when its two juncions are kept at different temperatures is called thermo e.m.f.
A thermocouple is comprised of at least two metals joined together to form two junctions. One is connected to the body whose temperature is to be measured; this is the hot or measuring junction. The other junction is connected to a body of known temperature; this is the cold or reference junction. Therefore the thermocouple measures unknown temperature of the body with reference to the known temperature of the other body.

Thank u for the answer.
Please post the answer for all the questions.
What is neutral temperature?
What is the rate of increase of thermo-e.m.f. with temperature at the neutral temperature of a thermocouple will be?