How much heat per second h (=qδt) flows from the boiling water to the ice-water mixture?

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.

Planck decided to assume that atoms could only vibrate at certain frequencies that were whole numbers eg 2f, 3f and so on. others used to think that atoms vibrate continuously

The sunlight shines uv radiation on earth,a microwave oven radiates waves on food

An electromagnet is a material in which the current produces electromagnetism and is passed to the core.  so to fill in the blanks, choices would be better if there were.an electromagnet is a magnet produced by electric current with a metal core