To determine the number of electrons needed to produce a charge of -1C, let's use the conversion factor:

`1 e= -1.6x10^(-19)C`

We have:

`-1C*(1e)/(-1.6x10^(-19)C)=6.25x10^18 e`

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**`6.25x10^18` electrons are needed to produce a charge of -1C.**

To determine the number of electrons needed to produce a charge of -1C, let's use the conversion factor:

`1 e= -1.6x10^(-19)C`

We have:

`-1C*(1e)/(-1.6x10^(-19)C)=6.25x10^18 e`

` `

**`6.25x10^18` electrons are needed to produce a charge of -1C.**