Statement I: Molar conductivity increases with decrease in concentration for weak electrolytes.
Statement II: The number of ions increases and the number of ions per unit volume decreases due to dilution. 

Given Statements:

Statement I: Molar conductivity increases with decrease in concentration for weak electrolytes.

Statement II: The number of ions increases and the number of ions per unit volume decreases due to dilution.

Analysis:

Statement I: Molar conductivity increases with decrease in concentration for weak electrolytes.

This is TRUE. For weak electrolytes, as concentration decreases, the ions are more dissociated because they are in a more dilute solution, which leads to an increase in molar conductivity. This is a characteristic behavior of weak electrolytes as they ionize more at lower concentrations.

Statement II: The number of ions increases and the number of ions per unit volume decreases due to dilution.

This is TRUE. When the solution is diluted, the total number of ions may increase as more of the electrolyte dissociates, but the number of ions per unit volume decreases due to the dilution of the solution. This is a direct consequence of dilution—ions are spread out over a larger volume.

Both statements are TRUE. However, Statement II does not directly explain Statement I. Statement I is primarily due to the increased ionization of weak electrolytes with dilution, while Statement II describes the physical effect of dilution (decreasing ion concentration per unit volume). Therefore, Statement II is not the exact explanation for Statement I.

Final Answer

If both the statements are TRUE but statement II is not the correct explanation of statement I.