What is the number of electrons in an atom that has 20 protons and 17 neutrons.

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

According to the tide table below what time of day will the highest tide occur?

According to coulomb's law, how would the electrical force between particles change if the product of their electrical charge increased?