What is the Sunday after Easter commonly called?

Divine Mercy Sunday

Which powerful sorceress helped Jason in his quest for the Golden Fleece but later turned vengeful? In 'Frozen,' who is Anna and Elsa's friendly snowman friend? What did Elisha sprinkle into a spring to make the water pure again near Jericho? What acronym-named train board game requires players to build rail networks across North America? What chemical element is represented by the symbol O?