Answer
a. Parallel.
b. 7.7pF to 35 pF.
Work Step by Step
a. We see that one set of four plates is connected together, and the other set of four plates is connected together. Each capacitor has the same voltage, so the capacitors are in parallel.
b. For capacitors connected in parallel, the equivalent capacitance is the sum of the individual capacitances. The area of overlap varies, which changes the capacitance.
$$C_{eq}=7C=7\epsilon_o\frac{A}{d}$$
Find the minimum equivalent capacitance.
$$C_{min}=7\epsilon_o\frac{A_{min}}{d}=7(8.85\times10^{-12})\frac{2.0\times10^{-4}m^2}{1.6\times10^{-3}m}=7.7\times10^{-12}F$$
Find the maximum equivalent capacitance.
$$C_{max}=7\epsilon_o\frac{A_{max}}{d}=7(8.85\times10^{-12})\frac{9.0\times10^{-4}m^2}{1.6\times10^{-3}m}=3.5\times10^{-11}F$$