Why the passengers are advised to remove the ink from their pens while going up to in an aeroplane ?

Give reason for the following case: The passengers are advised to remove ink from pen while going up in an aeroplane.

The passengers flying in aeroplane are advised to remove the ink from their pens while going up in the aeroplane , why?

Why is it not advisable to take a fountain pen while travelling in an aeroplane?

A parachute is advised to be used by a person, while jumping out of an aeroplane. Explain why?

Why are we advised not to talk while eating food ?

Why does an air passenger prefer a ball pen over a fountain pen ?