Question

At 7 degrees Celsius the volume of gas is 49 liters. At the same pressure its volume is 74 mL at what temperature

Answer 1

Charle's law gives the relationship between volume and temperature of gas.
It states that at constant pressure, volume of gas is directly proportional to temperature of gas.
V/T = k
where V - volume , T - temperature and k- constant 
$\frac{V1}{T1} = \frac{V2}{T2}$
parameters for the first instance are on the left side of the equation and parameters for the second instance are on the right side of the equation 
T1 - 7 °C + 273 = 280 K
substituting these values in the equation 
$\frac{49 mL}{280K} = \frac{74 mL}{T}$
T = 423 K
temperature in Celcius scale - 423 K - 273 = 150 °C