5. Mr (LiH2PO4) =

5. Mr (LiH₂PO₄) = Ar(Li) + 2 × Ar(H) + Ar(P) + 4 × Ar(O).
Ar(Li) = 7, Ar(H) = 1, Ar(P) = 31, Ar(O) = 16.
Mr (LiH₂PO₄) = 7 + 2 × 1 + 31 + 4 × 16 = 7 + 2 + 31 + 64 = 104.

Ответ: 104