From the information given, the original volume of the gas is 300ml at 17 degrees Celsius. The final volume at 10 degrees Celsius is unknown.
To find the final volume of the gas, we need to apply Charles law which is expressed as V1/T1 =V2/T2
Where V1 original volume
where T1 is orginal temperature
where V2 is final volume
where T2 is final temperatue
We need V2 so V2 = (V1 × T2) ÷ T1
V2 = 300 × 10 ÷ 17
V2 = 400 ÷ 17
V2 = 23.52
Volume at 10° C is 23.52 ml