Step-by-step explanation:
It is given that,
Capacitance,

Potential difference, V = 6.4 volts
Initial charge,



When the mica is introduced between the plates of capacitor, the capacitance increases by a factor of k. The dielectric constant of mica lies in between 6 - 8. Let k = 7 (say)
New capacitance,

Final charge,



So, when mica sheet is introduced, more charge will flow out of the battery. Hence, this is the required solution.