why should spare petrol for cars be carried in a metal rather than plastic container?

Explain why the inside of the car is a safe place during a thunderstorm.

calculate the charge on 4.0 * 10^20 protons.

Don't believe everything you read, or are asked to prove.

Almost containers of petrol (gasoline) in the USA are now made of plastic. There is nothing wrong with that, if a proper type of plastic is used.

The metal gasoline cans I used to have all became rusty and had to be thrown away.

In the inside of a car, you are not on a conductive path to the ground. The current will not go through you, it will go arund you.

Multiply that number of protons by the electron charge (e), but with a + sign.