Asolution is prepared by dissolving 1.25 grams of silver chromate in 1.5 liters of water. after the solution was prepared, an additional 250. ml of water was added to it. which of the following decreased; -moles of solute -mass of solute -molarity of solution -volume of solvent

-moles of solute - mol of solute was not changed because solute was not added or removed (1)
-mass of solute - mass of solute was not changed because solute was not added or removed
-molarity of solution - decreased, because,
Molarity= mol solute/ volume solution
mol of solute did not changed(1), volume of solution increased (2). Denominator increases, so fraction decreases.
-volume of solvent- volume of solvent is increased, because the solvent is water, and water was added (2)

Idid the calculation and i get 875,000,000 which can be written as 8.75 x 10^6?

It conforms what ever surface its in.