At what temperature, in kelvin, will a 250 milliliter cylinder containing 0.100 moles of helium gas have a pressure of 2.50 atmosphere? write your answer as a decimal number to three significant figures. given: r = 0.08205 liter · atmosphere/mole · kelvin

Which of the following statements is true? a. elements in the last period are radioactive. b. atomic weight is the same as atomic mass. c. elements in the same group have the same number of electron shells. d. atomic number equals the number of neutrons in the nucleus of an atom.

What are the spectator ions in 2h+ + so42- + ca2+ + 2r → caso4 + 2h+ + 21?

Astudent reacts 13 moles of iron with 21 moles of oxygen according to the following equation: