Which Bottle Rocket Fuel Achieves Higher Altitudes?

[AstroPascal]

Bottle Rocket Fuels (URGENT)

Assuming the same volume, which should travel higher - a bottle filled with a dense fluid or a bottle filled with a less dense fluid?
Thanks for reading!

 

[LawrenceC]

If you assume the nozzle is only convergent, the gas will exit the bottle at a mach number of unity.

What can you say about the speed of sound and the density of gases?
What is the upward thrust of the exiting gas in terms of exiting velocity?
How does the gas density affect the rocket weight?