1. The right answer is Solvent
The term "solution" would not be applicable here because it designates the solute + the solvent ".
In chemistry we prefer to use the term solvent rather than liquid.
The solubility of a compound can be defined as follows: a maximum amount (g or mole) of solute dissolved in 1 liter of saturated solution according to precise conditions of temperature, nature of the solvent and the solute.
2. The right answer is Reactant.
During a chemical transformation the atoms of the reagents combine in different ways to form the products but no atom disappears or does not appear so the total mass does not change.
During a chemical transformation, the total mass of the disappeared reagents is equal to the total mass of products formed.