Why does every human measurement have uncertainty associated with it? why must we manage the uncertainty during calculations?

Which electron configuration represents the electrons in an atom of sodium in the ground state at stp

Which liquid (h2o, h2o + soap, or h2o + salt) has the strongest cohesion and adhesion? (need now plz)

Which of the following is a physical change? a.burning a piece of wood b.sawing a piece of wood in half c.rust forming on an iron fence d.a copper roof changing color from orange to green