Answer:
even-handedness or impartiality
It represents Lady Macbeth's malaise and guilt awakening and driving her to insanity. In this scene, she "sees" blood on her hands, a metaphor for her guilt, and it cannot be washed off- the sin cannot be undone. After this scene, Lady Macbeth's strength runs out and is overcome with guilt to the point that she commits suicide.
Number 4. The infinitive is "to practice" it is "to" followed by a verb
