What is the mass percent of O in Al(OH)3​

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

What is the relation between concentration of reactants and the rate of chemical reaction?

According to the vsepr theory what is the shape of a molecule that has a central atom valence three other items with no lone pairs of electrons