Write the Nernst equation and compute the e.m.f. of the following cell at 298K:
`Sn(s)"|"Sn^(2+)(0.05M)"||"H^(+)(0.02M)"|"H_(2)`, 1 atm Pt
[Given : `E^(Theta)Sn^(2+)//Sn=-0.136V`]

Explanation

To solve the problem, we will follow these steps:

### Step 1: Write the half-reactions
The half-reactions for the cell are:
1. For tin (Sn):
\[ \text{Sn(s)} \rightarrow \text{Sn}^{2+} + 2e^- \]
...