4) Bring your charged balloon near the pile of salt and pepper particles. What happens? Which
pieces were picked up more easily? Is this a good way to separate salt and pepper if they
accidentally get mixed?

Explanation:

When a charged balloon is brought near a mixture of salt and pepper , the relatively light pepper gets attracted towards the balloon and the heavier salt is left behind.

The balloon is rubbed first which creates negative charge on it . When the charged balloon is brought near the mixture , both salt and balloon are charged oppositely so both of them feel force of attraction towards the balloon. But pepper is  more easily attracted because it is lighter than salt.

It is not a good way of separating them because some salt also get mixed with pepper because some salt is also attracted.

d) physical means can be used to separate the components of air.