The planet closest to the sun is mercury and this is because the order of the planets in the solar system, starting nearest the sun and working outward is the following: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and then the possible Planet Nine. If you insist on including Pluto, it would come after Neptune on the list.
Proteins
Proteins is the most thermogenic of all nutrients and macromolecules we eat. Thermogenesis is the generation of due to digestion and metabolism of food. Studies shows that proteins tend to be more thermogenic that carbohydrates and fats. This means that the calorie given of by proteins is converted and released as heat and less available for storage. This means that the stored energy formed from protein much of it is released as heat and unlike other macromolecules few of it is converted to a energy that can be stored.
Well I do know the answer to question #5 is temperature