What is the concentration of nitrate ions in a 0.225 msr (no3) 2 solution?

We are given that there are 2 moles of NO3 from the 0.225 M Sr (NO3) 2 solution. Therefore we simply use stoichiometry to solve this problem.

Concentration NO3 = 0.225 M Sr (NO3) 2 * (2 moles NO3 / 1 mole Sr (NO3) 2)

Concentration NO3 = 0.45 M