The correct option is
D In gas electrode, gas is indicated before electrode for cathode
Rules for Cell representation:
1. Anode half cell should be on left side and cathode half cell should be on right side.
2. Separation of two phase should be shown by vertical line
(∣). This line indicates phase boundary.
3. If various material present in the same phase, it should be shown together with commas (,).
4. The salt bridge is represented by double slash
(∣∣) between the two half cells.
5. The significant features of the substance like pressure of a gas, concentration of ions, etc. should be indicated in brackets immediately after writing the substance.
6. For gas electrode, gas should be indicated after electrode for anode and should be indicated before electrode for cathode.
H2 gas electrode for cathode is represented as
H+(aq)|H2(g)|Pt(s)
Hence, (a), (b) and (d) are true for cell represenation.