4. which of the following elements is stable?

a. fluorine, atomic number 9
b. carbon, atomic number 6
c. boron, atomic number 5
d. neon, atomic number 10

Which is a chemical property of iron? a. it forms iron oxide (rust) when exposed to moisture and air. b. it is a gray–black metal that is hard to the touch. c. it has a melting point of 2795°f (1536°c). d. it is a good conductor of heat

Chemical energy is a form of a. kinetic energy only. b. both potential and kinetic energy. c. neither potential nor kinetic energy. d. potential energy only. reset

Large helium-filled balloons are used to lift scientific equipment to high altitudes. what is the pressure inside such a balloon if it starts out at sea level with a temperature of 10.0ºc and rises to an altitude where its volume is twenty times the original volume and its temperature is – 50.0ºc ?