Infer why it is important to add sodium chloride to
water when making homemade ice cream.

the addition of sodium chloride to water effect a lowering of the melting point of water such that the liquid cream or water mixture tends to solidify upon churning when in thermal contact with the mix indigrents

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.  

u i forgot the answer?