Final answer:
The solvent for a Grignard reaction must be free of water because water reacts with and consumes the Grignard reagent, rendering it ineffective for the intended chemical reaction. The correct option is (c).
Step-by-step explanation:
The solvent for a Grignard reaction must be free of water because water consumes the Grignard reagent. Grignard reagents are highly reactive organomagnesium compounds, and in the presence of water, a Grignard reagent will react with water to form the corresponding hydrocarbon and magnesium hydroxide. This reaction effectively destroys the active Grignard compound and prevents it from reacting with the intended substrate.
When considering gases that react with water such as HCl or NH3, they demonstrate a much higher solubility than would be expected from Henry's law due to chemical reactions with the solvent, leading to ion formation. Similarly, the Grignard reagent, an organomagnesium compound, would rather react with water than stay dissolved in it. That's why it is crucial to keep the reaction environment completely anhydrous.
The correct answer to the question is 'C) water consumes the Grignard reagent'. If water is present, it will react with the Grignard reagent and as a result, the desired chemical reaction will not occur or will yield lower amounts of the intended product.