What is the chemical name for Se8O7​

Rutherford's experiment indicated that matter was not as uniform as it appears what part of his experimental results implied this idea

Can someone me with questions 15 to 17 plz.

Insoluble sulfide compounds are generally black in color. which of the following combinations could yield a black precipitate? check all that apply. na2s(aq)+kcl(aq) li2s(aq)+pb(no3)2(aq) pb(clo3)2(aq)+nano3(aq) agno3(aq)+kcl(aq) k2s(aq)+sn(no3)4(aq)