The $$\left(\frac{\partial E}{\partial T}\right)_P$$ of different types of half cells are as follows :
A: $$1 \times 10^{-4}$$, B: $$2 \times 10^{-4}$$, C: $$0.1 \times 10^{-4}$$, D: $$0.2 \times 10^{-4}$$
(Where E is the electromotive force). Which of the above half cells would be preferred to be used as reference electrode

We are given the temperature coefficients $$\left(\frac{\partial E}{\partial T}\right)_P$$ for four half-cells and need to determine which would be preferred as a reference electrode.

Understand the requirement for a reference electrode.

A reference electrode must have a stable and constant EMF that does not change significantly with temperature. Therefore, we need the half-cell whose EMF varies the least with temperature.

Compare the temperature coefficients.

The values of $$\left(\frac{\partial E}{\partial T}\right)_P$$ are:

A: $$1 \times 10^{-4}$$

B: $$2 \times 10^{-4}$$

C: $$0.1 \times 10^{-4} = 1 \times 10^{-5}$$

D: $$0.2 \times 10^{-4} = 2 \times 10^{-5}$$

Identify the smallest value.

The smallest temperature coefficient is for half-cell C with $$0.1 \times 10^{-4}$$.

This means half-cell C has the most stable EMF with respect to temperature changes, making it the best choice for a reference electrode.

The correct answer is Option C.