I don't no if this helps but the body heat from your hand causes the liquid to boil, which in turn makes the liquid evaporate, turning it to gas. The expanding gas pushes the liquid upwards and when you release your hand, equilibrium is re-established.
The answer is D. As the ambulance gets closer, the sound waves are compressed relative to the person; so the frequency increases.
1. b or c
2. c
3. a? or d
4.
5. a
Answer:
Only circuit A will contain to lit bulbs
