can an electroscope measure and detect  the nature of charge whether it is positive or negative  if yes then how?

yes because it is in meritnation

Good question

Yes, it can as when a substance with unknown charge is touched with the electroscope , the whole setup along with the gold leaf gets that charge and when a substance which as the negative charge and we know it ,is touched with the electroscope, if the gold leaf repels from the brass, we conclude that the first substance has negative charge and if the gold leaf is attracted towards the brass, it is positive also.

sorry if the image is not there.

Yes an electroscope can detect and measure the charge of an object To know about the type of charge you need to charge the electroscope and then touch the object with the brass disc of the electroscope and then observe what happens

Hope it helps .

Give all definition

What

lightning conductor is answer