In this step, you will create a model solution of pH = 7 with equal concentrations of Hf and OH-. The black beans will represent H+ ions and white navy beans will represent OH-ions. Click or tap the bag of black beans to add 50
of the beans to the beaker.

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

if you mean hydrogen and oxygen then water is the product

the answer is na (sodium)

i think it's c. if you look search electronic symbol on google and then click on wiki it shows you a