Electric current has both magnitude and direction. It is a

The charge flowing in a conductor varies with time as $Q = at - bt^2$. Then for current,which statement is incorrect?
$(A)$ decreases linearly with time
$(B)$ reaches a maximum and then decreases
$(C)$ falls to zero after time $t = a/2b$
$(D)$ changes at a rate $-2b$

The current in a wire varies with time according to the relation $I = 4 + 2t$. The quantity of charge which has passed through a cross-section of the wire during the time $t = 2 \, s$ to $t = 6 \, s$ will be .............. $C$.

Estimate the magnitude of current that passes through a wire, if $0.1 \text{ mol}$ of electrons flow through it in $40 \text{ min}$. (Assume Avogadro number $= 6 \times 10^{23}$) (in $\text{ A}$)

“In lightning in the sky,there is a steady flow of charge”. -True or False?

In a conducting region, $10^{19}$ electrons and $10^{19}$ protons move to the left, while $10^{19}$ $\alpha$-particles move to the right per second. The resulting electric current is $(e = 1.6 \times 10^{-19} \text{ C})$