which of the following does not have the same dimension?

2. Pressure = $\frac{Force}{Area}$ Stress = $\frac{Force}{Area}$ Youngs modulus : $\frac{Stress}{Strain}$ Since strain is dimensionless so all three have same dimension.

3. Electromotive force = $\frac{Energy}{Charge}$ ​

Potential difference = $\frac{W}{Q}$ which is same as Electromotive force. Electric voltage = $\frac{Electric Energy}{Charge}$ ​All three have same dimension.

4. Heat , Potential energy and work done all have same dimension.