Question

A simple dry cell cannot be used for a long time give reason

Answer 1

Dry cells can be used a long time, but only in certain conditions. Dry primary cells utilize chemical reactions that are difficult/impossible to reverse within the battery chemistry (but relatively high energy density), while secondary dry cells utilize reversible (but inefficient) chemistries which lead to their limited capacities.

The issue for both is the nature of dry cells you get a certain amount of loss when you reverse the reaction, which leads to faster depletion when discharging.

HOPE THIS WAS USEFUL.