Why is the use of iodised salt advisable?

Give uses of common salt.

Uses of common salt are-

Why it is not advised to wear polyester clothes while working in a kitchen?

Sleeping pills are recommended by doctors to the patients suffering from sleeplessness but it is not advisable to take its doses without consultation with the doctor. Why ?

Gurmit wanted to perform activity 16.8 using a laser torch. Her teacher advised her not to do so.Can you explain the basis of the teacher 's advise ?

Why is heavy water used as moderator?