PLEASE ANSWER QUICKLY. What is the energy of a photon with a frequency of 2.05 x 10^11? Pls show all your work

As a part of an experiment a student burns propane to produce carbon dioxide and water she remembers that she must follow the law conservation of matter when writing a balanced chemical equation which of these equation adheres to the law of conservation of matter

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

Your friend offers to show you an intrusive igneous rock. which of the following would you expect to see?