From AQA A2 chem textbook,
Calculate the emf of
2H+(aq) + Pb(s) ---> Pb2+(aq) + H2(g)
(The value for Pb2+ ---> Pb is +0.13)

The H+/H2 is 0 by definition, so therefore the emf must be -0.13 (due to the way the equation is written) but the answer in the book is 0.26 and has no working,

Could someone explain this or has the book got a mistake?
Thanks

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