You are given three beakers of unknown liquids. one beaker contains sugar water. without tasting the liquids, how could you identify the liquid in each beaker

You would observe, trying to identify if there's a minimum difference in each beaker. Like, colour, or using an bagueta (idk how to say it in english), churning it or something like that.

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

2h2o2--> 2h2o + o2

this reaction is of the spontaneous decomposition of hydrogen peroxide down into water and oxygen.

add 2 molecules of hydrogen peroxide and 2 molecules of water. since oxygen is naturally diatomic, the total number of atoms of each element is now the same on both sides of the equation so it is balanced.

this may not be entirely correct but let me know.