Which statement best describes how a Geiger counter works? Select one:
a. Water vapor condenses along a path traveled by ionizing radiation.
b. Particles ionized by radiation cause black streaks to appear on sensitive photographic paper.
c. Radioactive particles ionize argon gas in a tube and the resulting electric current is amplified and heard as a clicking sound.
d. A material sensitive to radioactive emissions glows when mixed with a radioactive substance.

)benzene and toluene form nearly ideal solutions. consider an equimolar solution of benzene and toluene. at 20 °c the vapour pressures of pure benzene and toluene are 9.9 kpa and 2.9 kpa, respectively. the solution is boiled by reducing the external pressure below the vapour pressure. calculate (i) the pressure when boiling begins, (ii) the composition of each component in the vapour, and (iii) the vapour pressure when only a few drops of liquid remain. assume that the rate of vaporization is low enough for the temperature to remain constant at 20 °c.