3. Which best describes the definition for the atomic mass of an element? A. It is a ratio based on the mass of the carbon-12 atom.

B. It is the sum of the protons. And neutrons in one atom of the element.

C. It is twice the number of protons in one atom of the element.

D. It is a weighted average of the masses of an element’s isotopes.

What will most likely happen in the absence of a cell membrane? a) photosynthesis will not take place. b) the cell will not store food, water, nutrients, and waste. c) energy will not be released during cellular respiration. d) substances will pass in and out of the cell in an uncontrolled manner.

Two people each hold the end of a rope and create waves by moving their arms up and down. this wave is best classified as a transverse wave because a) both the rope particles and the wave are moving in the same direction. b) the wave is moving up and down as the particles of the rope move horizontally. c) the wave is moving horizontally as the particles of the rope move up and down. eliminate d) the wave is moving in a parallel direction with the motion of the person's arms.

What happens in the particles of a gas when the gas is compressed