An 240. mL sample of oxygen at 90.00C and was cooled at constant pressure until it has a volume of 450.0 mL. What was the final Celsius temperature of this
gas? *

The final temperature : T₂ = 680.625 K

Given

V₁=240 ml

T₁ = 90 + 273 = 363 K

V₂ = 450 ml

Required

The final temperature

Solution

Charles's Law  

When the gas pressure is kept constant, the gas volume is proportional to the temperature  

Input the value :

T₂ = V₂T₁/V₁

T₂ = 450 x 363 / 240

T₂ = 680.625 K

- "the choice that is not an indicator of a chemical change is "state of matter changes". more common than not, chemical reactions produce energy in the form of light or heat. along with energy, they also produce a new substance called the product that could be in any state of matter (solid, gas, or liquid)."

that's what i got you can count the number of atoms