Question

why did the electric current is regarded as a fundamental quantity bit why not a derived quantity as it is equal to charge per second....... plz answer it appropriately.....,

Answer 1

The reason of adopting electric current as a fundamental unit lies in the convenience of measurement. Electric charge is often very difficult to measure as one needs very sensitive instruments to measure it. But to measure current, one can make use of its property to generate magnetic field, and generate heat.
Because one can measure the deflection of the ammeter, due to the force generated by the magnetic field and the temperature change generated due to heating wires, historically amperes were seen as more 'realistic' units in physics.