3 capacitors connected with a 6V battery as shown in the figure below
∴ Equivalent capacitance of 1nf and 2nF connected in parallel is given as, C′=(1+2)nF This equivalent C′ is connected in series with 3nF. So, the equivalent capacitance of the given circuit is Ceq=
(1×2)×3
(1+2)+3
=1.5nF Total charge on the capacitors =V×Ceq =6×(1.5nF)=9nC