Abottle is half-filled with a 50: 50 (mole-to-mole) mixture of n-heptane (c7h16) and n-octane (c8h18) at 25â°c. what is the mole ratio of heptane vapor to octane vapor in the air space above the liquid in the bottle? the vapor pressures of heptane and octane at 25â°c are 31 torr and 11 torr, respectively.

Answer is:  mole ratio of heptane vapor to octane vapor is 2,8 : 1.
p(C₇H₁₆) = 31 torr.
p(C₈H₁₈) = 11 torr.
x(C₇H₁₆) = 0,5.
x(C₈H₁₈) = 0,5.
p total = (x(C₇H₁₆) · p(C₇H₁₆)) + (x(C₈H₁₈) · p(C₈H₁₈)) = 0,5· 31 torr + 0,5·11 torr = 21 torr.
The mole fraction of heptane in the vapor is:
p(C₇H₁₆) ÷ p total) = 15,5 torr ÷ 21 torr = 0,74. 
The mole fraction of octane in the vapor is:
p(C₈H₁₈) ÷ p total = 5.5 torr ÷ 21 torr = 0,26.
Mole ratio heptane vapor ÷ octane vapor: 
0,74 ÷ 0,26 = 2,8.

D. most models represent a real world object in a simpler way

You would be correct, boiling water does disinfect contamination.    the property of disinfecting means to kill  germs, bacteria and other pathogens or contamination  that might cause an infection or cause a person to become sickly. a couple methods of disinfecting are using soap, other cleaning supplies or by simply "boiling" the contaminate.  the reason why boiling water disinfects certain attributes is because some cells cannot survive the heat and pressure.