The elements X and Y have spectra pictures as shown in the diagram below. W is the spectrum of a mixture of elements X and Y and a third element, Z. Use the diagram of the spectrum pictures to answer any questions that follow. Which diagram contains the spectra for elements X and Y?
A
I

B
II

C
III

D
IV

What term describes technology that operates on an atomic level

Correct relationship between molecular formula and empirical formula

)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.