Consider a solution of CO$_2$(g) dissolved in water in a closed container. Which one of the following plots correctly represents variation of $\log$ (partial pressure of CO$_2$ in vapour phase above water) [y-axis] with $\log$ (mole fraction of CO$_2$ in water) [x-axis] at
$25^\circ$C? 
Consider an A.P. $a_1,a_2,\ldots,a_n$; $a_1>0$. If $a_2-a_1=-\dfrac{3}{4}$, $a_n=\dfrac{1}{4}a_1$, and \[ \sum_{i=1}^{n} a_i=\frac{525}{2}, \] then $\sum_{i=1}^{17} a_i$ is equal to
