PLEASE ANSWER

A. Electromagnetic waves must travel through a medium, but mechanical waves do not require a medium.

B. Mechanical waves must travel through a medium, but electromagnetic waves do not require a medium.

C. Mechanical waves sometimes travel through a vacuum, and electromagnetic waves sometimes travel through matter.

D. Electromagnetic waves travel mostly through matter, and mechanical waves travel mostly through a vacuum.

Consider the nuclear equation below. 239 > x + 4 he 94 2 what is x? 1.235 cm 96 2.243 u 92 3.235 u 92 4.243 cm 96

Select the correct text in the passage. which sentences describe examples of sustainable living? i live in an old apartment building downtown, but my company is based in an office park on the outskirts of the city. i drive an old car that needs to be replaced. i plan to buy a hybrid for better gas mileage, but for now i am able to carpool with a couple of friends from work. the drive to the office park is about 45 minutes each way, but we do get to work in a modern building. the architects just received a leed certification for the design.

Which material burns faster? metal aluminum