how do i use the conversion on this question

Question

A closed container in lab contains a sample of oxygen gas. When the temperature in lab is 17.3 degrees Celcius, the pressure in the container is 2.10 atm. What would the pressure be if the temperature dropped to 24.3 degrees Celcius?

Answer 1

At constant V, and moles, P is proportional to T: (whatever multiplier apply to T, you apply to P)

P₂ = P₁(T₂/T₁)

If you use this kind of proportional thinking, you must use absolute units Kelvin = Celsius + 273.25 for temperature. The only time you need to worry about pressure units is when you use a gauge open to the atmosphere.

You should be able to figure it out from here. This is called Amonton's Law although some texts still say Gay-Lussacs. By the way, your temperature is going up, not down.