Verified answer

4

M(Ba(OH)2)=137+32+2=171

w(Ba)=137*100/171=80,1%

w(O)=32*100/171=18,7%

w(H)=2*100/171=1,2%

5

m(розчину)=3кг=3000г

m(солі)=3000*0,9/100=27г

m(H2O)=3000-27=2973г

V(H2O)=2973г/1г/мл=2973мл