As described in the problem introduction, a criterion for a dark band to appear at point P is that the phase difference between light arriving at point P from the top of the slit and light arriving at point P from the bottom of the slit equal 2π. What length of path difference d will give a phase difference of 2π?

The answer to this is decibel

Multiply the 3 dimensions, assuming it is a rectangular cuboid, to get the volume in cm³ divide mass by volume to get density in g/cm³

The answer is water molecules are split.cellular respiration and photosynthesis are complement  reactions to each other. these are reverse reactions. in cellular respiration glucose and oxygen yield water and carbon dioxide. so, when respiration begins,  glucose molecules are split. in the opposite reaction - in photosynthesis, carbon dioxide and water yield glucose and oxygen. thus,  when respiration begins, water molecules are split.