Step 1: Use the formula for electrochemical deposition.
The mass deposited is given by:
\[
m = Z \times I \times t
\]
where \( Z \) is the electrochemical equivalent, \( I \) is the current, and \( t \) is the time.
Step 2: Calculate the mass.
Substitute the values:
\[
m = 0.126 \times 5 \times 3600 = 0.378 \, \text{g}
\]
Final Answer:
\[
\boxed{0.378 \, \text{g}}
\]