Help me with the first question it’s 7 grade science

Which best describes the nucleus of an atom a. it is where all of the particle s of the atom are located b. it is the negatively charged part of the atom c. it is where the electrons and the protons are located d. it is the part of the atom with the greatest mass

The more rapidly sedimentation occurs, the more likely it is that the remains will successfully form a fossil. as sedimentation continues, what happens to the amount of weight settling onto the organism? stays the same increases decreases cuts in half

When an object is moving away from you while still making a sound, the pitch of the sound is perceived to a. lower b. unchanged c. fluctuating d.higher