Question

H3PO4(aq) + _Ca(s) → Ca(PO4)2 (aq) + _H2(8)

Answer 1

The balanced equation for the reaction is:

2H3PO4(aq) + 3Ca(s) → Ca3(PO4)2(aq) + 3H2(g)

Please note that the subscript 8 in H2(8) should be subscripted.