a solution is prepared by dissolving 15.0 grams of ni(no3)2 in enough water to make 250 ml of solution what is the molarity of this solution

I assume you mean Ni(NO3)2. In chemistry you need to find the caps key on your keyboard and use it. CO, Co, and co are not the same.

mols Ni(NO3)2 = grams/molar mass = ?
Then M = mols Ni(NO3)2/L solution = ?

0.0229 M

To find the molarity of a solution, you need to know the amount of solute (in moles) and the volume of the solution (in liters).

First, let's calculate the moles of Ni(NO3)2 using its molar mass. The molar mass of Ni(NO3)2 can be calculated as follows:

Ni: 58.69 g/mol
N: 14.01 g/mol
O: 16.00 g/mol

Molar mass of Ni(NO3)2 = (Ni: 1 * 58.69 g/mol) + (N: 2 * 14.01 g/mol) + (O: 6 * 16.00 g/mol)

Molar mass of Ni(NO3)2 = 164.85 g/mol

Next, we can calculate the moles of Ni(NO3)2 by dividing the mass of the compound by its molar mass:

moles of Ni(NO3)2 = mass / molar mass
moles of Ni(NO3)2 = 15.0 g / 164.85 g/mol

moles of Ni(NO3)2 ≈ 0.091 mol (rounded to three decimal places)

Now, we can find the molarity of the solution by dividing moles of solute by the volume of the solution in liters:

Molarity (M) = moles of solute / volume of solution (in L)
Molarity (M) = 0.091 mol / 0.250 L

Molarity (M) = 0.364 M (rounded to three decimal places)

Therefore, the molarity of the solution is approximately 0.364 M.