Question

raising the temperature of 25 l of helium in a constant pressure container from 100°c to 200°c
has no effect on the volume
reduces the volume
increases the volume to 200/100 x 25 l
changes the volume to 473/373 x 25 l

Explanation:

Step1: Convert Celsius to Kelvin

Charles's Law ($\frac{V_1}{T_1}=\frac{V_2}{T_2}$) requires temperature in Kelvin. $T_1 = 100 + 273=373\ K$, $T_2=200 + 273 = 473\ K$, $V_1 = 25\ L$.

Step2: Apply Charles's Law

From $\frac{V_1}{T_1}=\frac{V_2}{T_2}$, we can solve for $V_2$. Cross - multiply gives $V_2=\frac{T_2}{T_1}\times V_1$. Substitute the values: $V_2=\frac{473}{373}\times25\ L$.

Answer:

Changes the volume to $473/373\times25\ L$ (the fourth option).