A gauge records the pressure over atmospheric pressure (0kpa on the gauge is actually the atmospheric pressure and a reading of 276kpa is 276kpa over atmospheric pressure). That means that means that to find absolute pressure you just add atmospheric pressure (around 1atm (101kpa)) to 286kpa to get 387kpa. I hope this helps.
B .combustion because HOH and CO2 are the products of complete combustion
You are given a galvanic cell consists of a Ni²⁺/ Ni half-cell and a standard hydrogen electrode. Also, you are given that the half cell Ni²⁺/ Ni will act as an anode, and the standard cell potential is 0.26V. You are asked to find the standard reduction potential for the half cell Ni²⁺/ Ni.
You will have a half - reaction for both nickel and hydrogen
The conversion of the symbol Ni²⁺/ Ni half-cell is
Ni²⁺ + 2e⁻ → Ni (s) E = 0.26V
and the conversion of the standard hydrogen electrode (SHE) is
2H⁺ + 2e⁻ → H₂ (g) E = 0V
Since H⁺ ions is a it difficult to set up during the process, nickel will be deposited at the cathode side instead of the anode. Therefore, The standard electron potential of the nickel will have -0.26V.