The products of reaction are ZnSO4 and H2. Since ZnSO4 is in aqueous form (aq), therefore only H2 and water vapor contributes to the overall total pressure in the system.
Total Pressure = 764 torr = H2 partial pressure + Water partial pressure
Since Water partial pressure is 26.74 torr so,
H2 partial pressure = 737.26 torr = 0.97 atm