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$\begin{align}

& \text{A}\text{. 6}\text{.25}\times \text{1}{{\text{0}}^{18}}\text{ electrons}\text{.}{{\text{s}}^{-1}} \\

& \text{B}\text{. 2}\text{.25}\times \text{1}{{\text{0}}^{18}}\text{ electrons}\text{.}{{\text{s}}^{-1}} \\

& \text{C}\text{. 6}\text{.25}\times \text{1}{{\text{0}}^{14}}\text{ electrons}\text{.}{{\text{s}}^{-1}} \\

& \text{D}\text{. 2}\text{.25}\times \text{1}{{\text{0}}^{14}}\text{ electrons}\text{.}{{\text{s}}^{-1}} \\

\end{align}$

Answer
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Ampere is a unit of current. It is a SI unit. Ampere is also a fundamental unit. One ampere can be defined as the amount of current flow because of one coulomb of charge flowing through a point per second.

Now, current flow is due to the flow of the conducting electrons through a conductor. Amount of charge flowing through the conductor is dependent on the number of electrons flowing through a conductor.

Now, one ampere current can be defined as the amount of current produced due to the flow of one coulomb of charge through the conductor in one second. So, to find the number of electrons flowing per sec, we need the charge of one electron.

The charge of one electron is, $e=1.6\times {{10}^{-19}}C$.

So, in one coulomb of charge, the number of electrons will be,

$n=\dfrac{1C}{1.6\times {{10}^{-19}}C}=6.25\times {{10}^{18}}$

So, $6.25\times {{10}^{18}}$electrons give us charge of one coulomb. Flow of $6.25\times {{10}^{18}}$electrons per second through a conductor will give us one ampere of current.

The current through a conductor can be mathematically expressed as,

$I=\dfrac{Q}{t}$ , where I is the current in ampere, Q is the charge in coulomb and t is the time.

The current is directly proportional to the amount of charge through the conductor. If the charge of the particle flowing increases, the current through the conductor will also increase proportionally.