Chemical Reaction Types?

Question

Could you please helping me in identifying what types of reactions are those? (precipitation, oxidation-reduction, acid-base). Thank you!
1) 2KI + Pb(NO3)2 ----> 2KNO3 + PbI2
2) Na2CO3 + NiCl2 ----> 2NaCl + NiCO3
3) CuO + 2HNO3 ----> Cu(NO3)2 + H2O
4) BaCl2 + Na2SO4 ----> BaSO4 + 2NaCl

Thank you!

Answer 1

1) ppt
2) ppt
3) acid-base
4) ppt
(none change ox #, so no redox