The Goddess Test by Aimée Carter
When Kate agrees to take the Goddess Test, she doesn't know every girl who has taken it has died...
It's always been just Kate and her mom, but now her mother is dying. Her last wish is to move back to her childhood home, so Kate's going to start at a new school with no friends, no other family and the fear her mother won't live past the fall.
Then she meets Henry. Dark. Tortured. And mesmerizing. He claims to be Hades, god of the Underworld, and if she accepts his bargain, he'll keep her mother alive while Kate tries to pass seven tests.
Kate is sure he's crazy--until she sees him bring a girl back from the dead. Now saving her mother seems amazingly possible. If she succeeds, she'll become Henry's future bride--and a goddess. But what Kate doesn't know is that no one has ever passed the Goddess Test.