a teacher cut an apple into three wedges of the same size. SHe dipped one wedge in lemon juice dipped another in water, and left one alone. Then she left the wedges on a paper towel on her desk. After 1 hour, only the wedge that had been dipped in lemon juice was still yellow. The other two wedges had turn brown

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 are the primary responsibilities of a chemical engineer involved in "r& d"? develop large scale manufacturing operations discover new products and processes training of new chemists determine products needed by consumers

State one important difference between a physical change and a chemical change?