The Death of Ms. Smith

Answer: Static. Static electricity makes hair stand on end. “Whisper between radio stations” points to the hissing noise called radio static. “Refuse to change” uses the other meaning of static: something fixed or unchanging. The riddle hinges on the word “static” having both electrical and descriptive senses.

Answer: A clock.  "Not a bird but I can fly through time": This is a metaphorical use of "fly". A clock doesn't physically move through the air, but the passage of time is often described as "flying" (as in the saying, "time flies").  "Hands moving, moments chime": A clock typically has "hands" that move to indicate the time, and some clocks "chime" to mark the hour or specific intervals. The riddle uses personification and metaphor to describe a clock's function in a creative way.

Answer: The answer is “a whip.” Multiple riddle collections list the solution as a whip for this exact clue set.  Leathery snake: A whip is often made of leather and long, flexible, and sinuous—like a snake. Stinging bite: The crack of a whip delivers a sharp, stinging strike. Coiled up: Whips are commonly stored coiled. Unless I must fight: It stays coiled until it’s needed, then uncoils for use (historically in control, sport, or combat).

Answer: An alarm clock. “It keeps something that cannot be kept”: Time can’t be held; a clock only measures it as it slips by. “And wakes you when you have slept”: The alarm rings to wake you. “It may go slow or stop at times”: Clocks can run slow or stop (dead battery, mechanical hiccup). “But even then it chimes”: Many clocks still chime or ring on the hour/alarm, even if their timekeeping isn’t perfect.