Question
Answers

Which is not true for a standard hydrogen electrode?
A.It can act both as a cathode and anode.
B.The temperature is 273K.
C.The pressure is 0 atm.
D.It contains a metallic conductor which does not absorb hydrogen.

Answer Verified Verified
Hint: 'SHE' refers to the standard hydrogen electrode.
It is a platinum electrode dipped in 1 M solution of ${ H }^{ + }$ ion (1 M HCl) at ${ 298 K }$ and hydrogen gas bubbled at 1 atm pressure. It acts as a reference electrode to find out the potential of the other half cell.

Complete answer:
Standard hydrogen anode which is called SHE which comprises a Platinum terminal secured with a platinum black covering. This platinum terminal is dipped in a 1M arrangement of ${ H }^{ + }$ particles( generally in HCl). Hydrogen gas is gone through it at 298K and at 1 atmospheric pressure is kept up in it. Hydrogen atoms are adsorbed on the Pt terminal and carry on as a ${ H }_{ 2 }$ plate. So it has a platinum metallic channel and absorbs hydrogen gas.

Hence, the correct option is B, C, and D.

Additional Information:
Limitations of Standard Hydrogen Electrode:
It is very difficult to assemble the apparatus.
It is difficult to maintain the pressure of ${ H }_{ 2 }$ gas of 1 atm throughout and also the concentration of ${ H }^{ + }$ ion of 1 M.
H2 electrodes cannot be used in the presence of an oxidizing agent.
Impurities that are present in hydrogen flow may create the poison for the platinum electrode and further which will alter the potential value.

Note: The possibility to make a mistake is that you may not choose option B. But the temperature required in Standard Hydrogen Electrode is ${ 25 }^{ \circ }{ C }$ or ${ 298K }$ not at ${ 273K }$.