An air-filled parallel-plate capacitor with plate area \(A\) and plate separation \(d\) has initial capacitance \(C_0\) and stores charge \(Q_0\) when connected to a battery of potential difference \(V_0\). While remaining connected to the battery, a slab of dielectric material with dielectric constant \(\kappa\) and thickness \(d\) is inserted so that it fills half of the area between the plates, as shown in the figure. Which of the following correctly gives the new total capacitance \(C'\) of the capacitor and the new total stored charge \(Q'\) in terms of initial quantities and \(\kappa\)?