If the temperature of a 1.75 liter sample of gas is changed from 30.0°c to 20.0°c at constant pressure, what will be the new volume? question 3 options:

According to Charles' law, "at constant pressure the volume of a gas is directly proportional to absolute temperature".

So, for a gas, initial and final states are given as,

                      V₁ / T₁  =  V₂ / T₂

Data Given:
                   V₁  =  1.75 L

                   T₁  =  30 °C + 273  =  303 K

                   V₂  =  ?

                   T₂  =  20 °C + 273  =  293 K

Solving Eq. 1 for V₂,

                        V₂  =  V₁ T₂ / T₁

Putting Values,

                        V₂  =  (1.75 L ×  293 K) ÷ 303 K

                        V₂  =  1.69 L
Result:
            As temperature is decreased so volume has also decreased to 1.69 L.