12. If a reaction is exothermic, a) It takes more energy to break the bonds of the reactants than is released when the bonds in
the products are formed
b) More energy is released when the bonds in the products are formed than is used to break
the bonds in the reactants
c) The same amount of energy is used to break the bonds of the reactants as is
released when the bonds in the products are formed
d) The temperature goes down

Blank allows you to do calculations for situations in which only the amount of gas is constant a)boyle's law b)combined gas law c)ideal gas law d)dalton's law

Achange in the number of neutrons in an atom will change an blank . when the number of protons changes in an atom, a new element will form.

)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.