a.
1.
Evaporable, vaporizable, vaporable.
2.
Airy, gay, lively, jolly, sprightly, vivacious, buoyant, full of spirit, jocund.
3.
Fickle, changeable, giddy, inconstant, flighty, reckless, capricious, unsteady, whimsical, humorsome, wild, hare-brained.