The universal gas constant $R$ is defined as:

In terms of Charles' law,explain why $-273.15 \,^{\circ}C$ is the lowest possible temperature.

If the density of a gas at $27\,^{\circ}C$ and $2\, atm$ is $5.46\, g/L$,then calculate the density of the gas at $STP$. (in $, g/L$)

At $400 \, K$ temperature,$200 \, mL$ of $N_2$ gas has a pressure of $1.5 \, bar$. Find the volume of $N_2$ gas at $STP$. (in $, mL$)

$A$ certain mass of a gas occupies a volume of $2 \,L$ at $STP$. To what temperature must the gas be heated to double its volume, keeping the pressure constant?

Identify the correct observation with respect to the given graphs.