Which of the following are NOT SAFE things to do, as we might get an electric shock? 1) Touching the switch of a geyser with dry hand.
2) Standing on a wooden stool to check a plug point.
3) Poking a metal rod into an electrical socket.
4) Touching the water in which an immersion heater is kept.

Before it was launched, a helium-filled balloon had a pressure of 201 kpa at a temperature of 27°c. at an altitude of 15,000 m, the pressure had decreased to 2.5 kpa and the temperature had dropped to -14 °c. the volume of the balloon increased to 59.3 m3. what is the original volume of the balloon? 13 m3 0.85 m3 0.077 m3 1.17 m3