Calculate the ∆h for the following reaction: no + o à no2 you are given these three equations: o2 à 2o ∆h = +495 kj 2o3 à 3o2 ∆h = -427 kj no + o3 à no2 + o2 ∆h = -199 kj

)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.

The semi-conductors on the periodic table are classified as

Which of the following isotopes has the same number of neutrons as phosphorus-31?