Statement I: A negative value of standard reduction potential means that reduction takes place on this electrode with reference to standard hydrogen electrode

Statement II: The standard electrode potential of a half-cell has fixed value

Statement I is false but Statement II is correct

The correct answer is option 4. Statement I is false, but Statement II is correct.

Statement I: A negative value of standard reduction potential means that reduction takes place on this electrode with reference to the standard hydrogen electrode.

The standard reduction potential is a measure of the tendency of a chemical species to be reduced, measured under standard conditions (298 K, 1 atm pressure, and 1 M concentration). The standard hydrogen electrode (SHE) is assigned a potential of 0.00 V, and all other electrode potentials are measured relative to it.

A negative standard reduction potential means that the species is less likely to gain electrons (be reduced) compared to hydrogen ions. In other words, it is less favorable for reduction. Instead, such a species is more likely to lose electrons (be oxidized). This is because a more negative potential indicates a weaker tendency to undergo reduction.

The statement implies that a negative standard reduction potential favors reduction, which is incorrect. It actually indicates that the reduction is less favorable compared to the SHE. Hence, a substance with a negative standard reduction potential would prefer oxidation rather than reduction when compared to the SHE.

Statement II: The standard electrode potential of a half-cell has a fixed value.

The standard electrode potential is a specific, intrinsic value for a given half-cell reaction under standard conditions. This value is determined experimentally and is used as a reference point for predicting and comparing the behavior of different electrochemical reactions.  For a given half-cell reaction, the standard electrode potential is constant under the defined standard conditions. This makes it a reliable reference for comparing the tendencies of different species to be reduced or oxidized.

Since Statement I is false and Statement II is correct, the correct answer is: Statement I is false but Statement II is correct.