Asample of nitrogen gas has the temperature drop from 250.°c to 150.°c at constant pressure. what is the final volume if the initial volume is 310. ml?

Charles law gives the relationship between temperature of gas and volume of gas.
It states that for a fixed amount of gas, temperature is directly proportional to volume of gas.
V / T = k
where   V- volume , T - temperature and k - constant 

parameters for the first instance are on the left side and parameters for the second instance are on the right side of the equation.
T1 = 250 °C + 273 = 523 K
T2 = 150 °C + 273 = 423 K
Substituting the values in the equation,


V = 251 mL
the new volume is 251 mL 

It conforms what ever surface its in.