Types of emissions from volcanoes and rate them according to how dangerous they have been to humans?

Two friends at different locations want to communicate with each other by sending low energy signals. which of the following methods can they use to communicate? a) produce x-rays using colliding electrons and send them to radios, which capture sound b) send messages using infrared radiation, which travel in the form of waves c) send radio waves through intervening media like radio and television d) produce sound waves using microwaves from heated objects

Esign techniques and materials that reduce the negative environmental impact of a structure are referred to as

Drive down any three characteristic of modern periodic table