Julie blows a bubble. At first, the pressure of the gas in the bubble is 4kPa. The bubble floats into the air and expands. When it gets to the top of a tree the bubble has a pressure of 2kPa and a volume of 3.5m³. Assuming a constant temperature, what was the volume in m³ of the bubble when it was first blown? Give your answer to three significant figures.

Two models of the same compound are shown. in what way is model b better than model a? model b shows the types of elements in the compound, but model a does not. model b shows the three-dimensional shape of the molecule, but model a does not. model b shows how the atoms in the molecule are connected, but model a does not. model b shows the number of atoms of each element in the molecule, but model a does not