An object that could be considered as negatively charged would be when it has an excess of an electron in its atom. However, when it loses an electron, it could go back to its stable state which is "uncharged" or when there is an excess proton, it could be a positively charged object.
Answer:
Yes you can. The charging current will be the lowest of the two current ratings of device and charger. The charger and the phone have complex internal circuitry that enable this behaviour.
But using a weaker charger for your phone will only lengthen charging time. And using a stronger charger than that the phone will accept doesn't affect charging at all and only wastes money.
Because fossil fuels are non-renewable resources.
This means, if we run out, we will not be able to reproduce it.
It would be the last that exists. (For oil, it'd be for the next few hundred years.)