\(a.m_{CuSO_4}=n.M=0,3.160=48\left(g\right)\)
\(b.n_{CaCO_3}=\dfrac{9.10^{23}}{6.10^{23}}=1,5\left(mol\right)\\ m_{CaCO_3}=n.M=1,5.100=150\left(g\right)\)
\(c.n_{MgCl_2}=\dfrac{1,5.10^{22}}{6.10^{23}}=0,025\left(mol\right)\\ \Rightarrow m_{MgCl_2}=n.M=0,025.95=2,375\left(g\right)\)