`a)n_[NaCl]=0,75.0,5=0,375(mol)`
`=>m_[NaCl]=0,375.58,5=21,9375(g)`
`b)n_[KNO_3]=2.0,5=1(mol)`
`=>m_[KNO_3]=1.101=101(g)`
`c)n_[CaCl_2]=0,1.0,25=0,025(mol)`
`=>m_[CaCl_2]=0,025.111=2,775(g)`
`d)n_[Na_2 SO_4]=0,3.1,5=0,45(mol)`
`=>m_[Na_2 SO_4]=0,45.142=63,9(g)`