What part of the heart receives oxygen rich blood from the lungs and squeezes it into the right ventricle?

This is the part of the heart on the left side of the heart that receives oxygen-rich blood from the pulmonary vein that is responsible for then moving the blood into the left ventricle. It is relaxed with blood and contracted without any blood present.

2%? i tried finding the exact sorry if it's not 100% correct ; -;

the three components of a nucleotide are the nitrogenous base, the phosphate group and the five-carbon sugar.