Ethylene glycol is a commonly used car antifreeze agent. Calculate the minimum amount of ethylene glycol that must be added to 3 kg of pure water in order to prevent freezing of the mixture for temperatures down to 244.3 K. Also calculate the boiling point of this mixture. The molar heat of melting of ice is 6.01 kJ/mol, and the molar heat of vaporization of water is 40.65 kJ/mol.

Select the correct value for the indicated bond angle in each of the compounds. o−o−oo−o−o angle of o3 90° 109.5° < 109.5° 120° < 120° 180° f−b−ff−b−f angle of bf3 180° < 109.5° < 120° 120° 109.5° 90° f−o−ff−o−f angle of of2 < 120° 120° 90° 109.5° 180° < 109.5° cl−be−clcl−be−cl angle of becl2 90° 109.5° 180° 120° < 109.5° < 120° f−p−ff−p−f angle of pf3 90° 109.5° < 109.5° 180° 120° < 120° h−c−hh−c−h angle of ch4 90° < 109.5° 180° 120° < 120° 109.5°