$A$ metallic conductor of non-uniform cross-sectional area is subjected to a constant potential difference. Which of the following quantities remains constant along the conductor?

The electric current in a conductor varies with time $t$ as $I = 2t + 3t^2$,where $I$ is in amperes and $t$ is in seconds. Find the total charge $Q$ (in $C$) that passes through the cross-section of the conductor from $t = 2 \ s$ to $t = 3 \ s$.

Explain the current formed in solid conductors in the presence of an external electric field.

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 $(e = 1.6 \times 10^{-19} \text{ C})$

In an electrolyte,$3.2 \times 10^{18}$ bivalent positive ions drift to the right per second,while $3.6 \times 10^{18}$ monovalent negative ions drift to the left per second. Then the current is:

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 $-2b$