Fill in the missing reactant and then balance each equation. k(s) + → koh(aq) + h2(g) k (s) + 3h2o →2koh (aq) + 2h2 (g) bi(no3)3(aq) + → bi2s3(s) + hno3(aq) hno3(aq) + → ba(no3)2(aq) + h2o(l)

1) 2K(s) + 2H₂O(l)→ 2KOH(aq) + H₂(g)
This is a single replacement reaction where K reacts with H₂O , displaces the H⁺ ion in water and combines with OH⁻ to form a base.

2) 2Bi(NO₃)₃(aq) + 3H₂S(g)→ Bi₂S₃(s) + 6HNO₃(aq)
This is a double displacement reaction where the ions are exchanged and form new compounds. Since ions are exchanged between 2 compounds its called double displacement.

3) 2HNO₃(aq) + Ba(OH)₂ → Ba(NO₃)₂(aq) + 2H₂O(l)
This is an acid base reaction where nitric acid and barium hydroxide react to form the respective salt and water

Filled   missing  reactant    and balanced    equation

2K(s)+  2H2O(l)  --->  2 KOh(aq)  +  H2 (g)

2Bi(No3)3(aq)  + 3H2S(g)>   Bi2S3  + 6  HNO3(aq)

2HNO3(aq) +Ba(OH)2(aq)  > Ba(NO3)2 (aq) +  2H2O(l)

in equation  above  the  missing   reagent  in  first  equation  is  H20,  second  is   h2S  while  the  third  is  Ba(OH)2

They are held together by chemical bonds. i am pretty sure.