(Mr) - масса всей молекулы Mr(H2O) = 2*Ar(H)+ Ar(O) = 2*1+16=18
MgCl2=
Ca(OH2)=
Al2O3=
H3BO3=
CuSo4=​

1) Mr(H₂O) = 2Ar(H)+Ar(O) = 2×1+16 = 2+16 = 18

2) Mr(MgCl₂) = Ar(Mg)+2Ar(Cl) = 24+2×35,5 = 24+71 = 95

3) Mr[Ca(OH)₂] = Ar(Ca)+2Ar(O)+2Ar(H) = 40+2×16+2×1 = 40+32+2 = 74

4) Mr(Al₂O₃) = 2Ar(Al)+3Ar(O) = 2×27+3×16 = 54+48 = 102

5) Mr(H₃BO₃) = 3Ar(H)+Ar(B)+3Ar(O) = 3×1+11+3×16 = 3+11+48 = 62

6) Mr(CuSO₄) = Ar(Cu)+Ar(S)+4Ar(O) = 40+32+4×16 = 40+32+64 = 136