1. SAT 10 Problem words REND – p.t.: They rent the cloth to shreds.
We observed with tears in our eyes the mourners rending their clothes in grief.
BANEFUL -- Reading Wuthering Heights proved baneful to some students’ sleep for they were haunted by Catherine’s ghost.
DESIST -- Desist from making so much racket, please; I am trying to concentrate!
INSULARITY -- Her insularity comes from never interacting with people, watching the news, or partaking in any social, political or religious activities.

2. Baneful – most often used as a noun: bane
Potable – used to describe water (as in safe to drink)
Preponderance – used with “of” (the preponderance of evidence points to his guilt)
Exacerbate – be specific about what is being exacerbated (Her screaming only exacerabeted the chaos and pandemonium at the scene where the accident occurred.)
Foible – usually refers to flaws in humans.
Effrontery – a noun, not an adjective.