Bài 7.3:
a) Ta có: \(m_{dd}=m_{NaNO_3}+m_{H_2O}=50+200=250\left(g\right)\)
b) \(C\%_{NaNO_3}=\dfrac{50}{250}\cdot100\%=20\%\)
Bài 7.4:
Ta có: \(n_{CuSO_4}=\dfrac{16}{160}=0,1\left(mol\right)\) \(\Rightarrow C_{M_{CuSO_4}}=\dfrac{0,1}{0,2}=0,5\left(M\right)\)