Which of the following is an example of an element: A) H₃O
B) He
C) Ca₂CO₃
D) CaCl₂
PLEASE ANSWER QUICKLY

Give more examples of this type of heat transfer:

A2-kg bowling ball is 1 meter off the ground on a post when it falls. just before it reaches the ground,its traveling 4.4 m/s. assuming that there is no air resistant, which statement is true a. the initial potential energy is less then the final kinetic energy b. the mechanical energy is not conserved c. the mechanical energy is conserved d. the initial potential energy is greater than the final kinetic energy

Gene expression control that occurs during the generation of rna is a. controlled at transcription b. control before transcription c. controlled after transcription d. controlled after translation