Why are some amino acids described as essential amino acids? a. They are the ones most used in the body.
b. They can be stored in the body.
c. They are the only ones needed by the body.
d. They cannot be made by the body.

Which statement describes how phase changes can be diagrammed as a substance is heated? the phase is on the y-axis and the temperature is on the x-axis. the temperature is on the y-axis and the phase is on the x-axis. the time is on the y-axis and the temperature is on the x-axis. the temperature is on the y-axis and the time is on the x-axis.

For ai it's atomic number is 13 and it's mass number is 27 how many neutrons does it have

Atrain travels 74 kilometers in 3 hours, and then 81 kilometers in 5 hours. what is its average speed?