What is the standard cell potential of a cell made of theoretical metals Ma/Ma

and Mb/Mb

if the reduction potentials are - 0.19 V and - 0.8

0.61

Explanation:

Flip the sign of the value which is most negative. This means that the metal is undergoing oxidation rather than reduction because it is more reactive. In this case - 0.8 becomes 0.8.

Add the two values together

-0.19+0.8

=0.61